Gamma Spectroscopy Lab Part 1: Background Notes & Theory

Gamma Spectroscopy Lab Part 1: Background Notes & Theory

The following is an ongoing build diary for my gamma spectrometer lab, which is why some things are in past/future tense since portions were typed before/during/after setting up various equipment. 

Here is the end result I wanted: a radioactive sample in a lead shield pig > measured by a Nai(TL) scintillation crystal detector > powered by the GS-1100A pmt driver > the signal is fed backwards through the GS-1100A to the computer running PRA or Theremino > which displays gamma energy lines on the screen.

The GS-1100A is powered by the desktop computer's USB port. The GS-1100A is what provides the high voltage to run the NaI(TL) detector. The GS-1100A is also what converts the NAi(TL) scintillator's output to sound, which is then fed back to the computer's mic/line input.

Scintillation Detectors (Not Geiger Counters)

Geiger counters give a click. Sometimes a lot of clicks, sometimes just a few. And that's all they do.

Gamma Spectroscopy takes a click and analyzes that click, developing it into a waveform shape that can be analyzed so minutely that you can tell what element/radioisotope you're measuring. It does this by calculating the spectrum of the radioactive source.

Geiger Counter = "Lots of clicking!"  vs  Gamma Spectrometer = "You've got plutonium!"

Here's the basics of gamma spectrometry, stated in various ways but saying the same thing :

A gamma wave hits the scintillator crystal which glows a little. The Photo Multiplier Tube amplifies this glow and change it to voltages which are read by the Multi Channel Analyzer and output to a computer screen in the form of an x/y waveform graph.

Gamma Ray > Scintillator > Photo Multiplier Tube > Multi Channel Analyzer > Display.

       

 Gamma Ray > Scintillator > PMT > MCA > Display.

Gamma Ray > photon > photo-electrons > electrons > voltage > display.

Gamma rays are waves of photon energy. A photon is a packet of light energy. A Gamma ray is a certain frequency of light energy/photon. Different wavelengths of energy are: visible light, UV light, x-rays, gamma rays, FM and AM radio, etc.

Gamma rays/photons have ZERO mass. They have no electrical charge (neutral). As such they move ONLY at the speed of light and never slow down. They can be scattered (bounced in a different direction losing none or some of its energy) or absorbed (it is destroyed and ALL its energy is transferred to whatever it hits and either knocks off an electron which is then called a photo-electron, or it splits into an electron + positron itself).

Thus, like the rest of the spectrums of light the question remains, "is it a wave or a particle?" At different times it behaves like both!


In our setup a gamma ray hits the scintillator crystal. The Scintillator crystal gives off light (photons). The photons enter the Photo Multiplier Tube. Inside the Photo Multiplier Tube there is a dynode. Each photon (sometimes they call this a "photo-electron") hits a metal plate (dynode) and turns into something like 10 impact electrons. There are many of these dynode plates, each one giving off more and more impact electrons as the energy travels through the PMT. At the other end of the PMT comes the electrons that are now around 1,000,000 times more numerous. NaI(Tl) gives off 42,000 photons per MeV; so 42 photons per KeV. The multi channel analyzer then sorts these voltages and sends the info to a display. The display can be a computer screen showing a wavelength in x/y axis. Each radioactive substance has a unique wavelength/shape and can thus be identified.

This is very cool so, of course I needed to set up a gamma spectroscopy lab in my house. First I'd need a radiation probe that has a scintillation crystal instead of a Geiger-Mueller (GM) Tube. GM tubes just give a click, no other usable information. Different crystals are better suited to reading different power ranges of gamma energy. 


I snagged this chart of Gamma Energies from Cal State Polytech Professor Peter Siegel's Biology 431 Study Guide from the Physics Department at Cal Poly Pomona. This lists the gamma energy of various radioactive substances. Of note for me are AM-241, LU-176, the various U- uranium isotopes and the old stand by: Radium.

Note that it gives the energy, but not the wavelength since gamma waves are around 0.1nm anyway. We're talking about Kilo electron Volts (KeV) here. This is not like my other spectrometers that give nice, simple colored lines that are held up to a nano meter scale ("green means the element mercury"). What will have is, say radioactive potassium (K-40) that upon decaying it gives off a neutrino and a 1460 KeV gamma ray. That 1460 will show up on our graph and we'll know we have Potassium K-40.

Gamma Energy (KeV)	Nuclide	Half-Life	Percent Yield per decay
8	Er-169	9.4 days	0.3
22	Sm-151	87 years	4
24	Sn-199m	250 days	16
30	Ba-140	12.8 days	11
31	Mg-28	21 hours	96
35	I-125	60 days	7
35	Te-125m	58 days	7
37	Br-80m	4.38 hours	36
40	Rh-103m	57 minutes	0.4
40	I-129	1.7×107 years	9
47	Pb-210	21 years	4
51	Rh-104m	4.41 minutes	47
53	Te-132	78 hours	17
58	Gd-159	18.0 hours	3
58	Dy-159	144 days	4
59	Te-127m	109 days	0.19
60	Am-241	458 years	36
63	Yb-169	32 days	45
63	Th-234	24.1 days	3.5
68	Ta-182	115 days	42
68	Ti-44	48 hours	90
70	Sm-153	47 hours	5.4
77	Pt-197	18 hours	20
77	Hg-197	65 hours	18
78	Ti-44	48 hours	98
80	Ba-133	10.51 years	36
81	Ho-166	26.9 hours	5.4
81	Xe-133	5.27 days	37
84	Tm-170	130 days	3.3
84	Th-228	1.90 years	1.6
87	Eu-155	1.81 years	32
88	Pd-109 / Ag-109m	13.47 hours / 40 seconds	5
Gamma Energy (KeV)	Nuclide	Half-Life	Percent Yield per decay
88	Cd-109 / Ag-109m	453 days / 40 seconds	5
88	Lu-176m	3.7 hours	10
91	Nd-147	11.1 days	28
93	Th-234	24.1 days	4
95	Dy-165	139.2 minutes	4
99	Gd-153	242 days	55
99	Au-195	183 days	10
100	Pa-234	6.75 hours	50
103	Sm-153	47 hours	28
104	Sm-155	23 minutes	73
105	Eu-155	1.81 years	20
113	Lu-177	6.7 days	2.8
122	Co-57	270 days	87
122	Eu-152	12 years	37
123	Eu-154	16 years	38
124	Ba-131	12 days	28
128	Cs-134m	2.9 hours	14
129	Os-191	15 days	25
133	Hf-181	42.5 days	48
134	Ce-144	284 days	11
136	Hg-197m	24 hours	42
137	Re-186	90 hours	9
140	Tc-99m	6 hours	90
143	U-235	7.1 x 108 years	11
145	Ce-141	33 days	48
147	Ta-182m	16.5 minutes	40
150	Te-131	25 minutes	68
150	Cd-111m	48.6 minutes	30
150	Kr-85m	4.4 hours	74
Gamma Energy (KeV)	Nuclide	Half-Life	Percent Yield per decay
155	Re-188	16.7 hours	10
158	Au-199	75.6 hours	37
163	Ba-140	12.8 days	6
164	Xe-131m	11.8 days	2
166	Ba-139	82.9 minutes	23
172	Ta-182m	16.5 minutes	40
185	U-235	7.1 x 108 years	54
186	Ra-226	1602 years	4
191	Mo-101	14.6 minutes	25
191	Pt-197	18 hours	6
192	In-114m	50.0 days	17
198	Yb-169	32 days	35
208	Lu-177	6.7 days	6.1
210	Ge-77	11.3 hours	61
215	Hf-180m	5.5 hours	82
215	Ru-97	2.9 days	91
230	Te-132	78 hours	90
233	Xe-133m	2.26 days	14
239	Pb-212	10.64 hours	47
239	As-77	38.7 hours	2.5
246	Sm-155	23 minutes	4
247	Cd-111m	48.6 minutes	94
250	Xe-135	9.2 hours	91
255	Sn-133	115 days	1.8
263	Ge-77	11.3 hours	45
265	Ge-75	82 minutes	11
265	Se-75	120.4 days	60
279	Hg-203	46.9 days	77
284	I-131	8.05 days	5.4
286	Pm-149	53.1 hours	2
293	Ce-143	33 hours	46
295	Pb-214	26.8 minutes	19
Gamma Energy (KeV)	Nuclide	Half-Life	Percent Yield per decay
299	Tb-160	72.1 days	30
305	Kr-85m	4.4 hours	13
307	Tc-101	14.0 minutes	91
308	Er-171	7.52 hours	63
310	Pa-233	27.0 days	44
317	Ir-192	74.2 days	81
319	Nd-147	11.1 days	3
320	Cr-51	27.8 days	9
325	Sn-125m	9.7 minutes	97
328	Ir-194	17.4 hours	10
333	Hf-180m	5.5 hours	93
335	Cd-115 / In-115m	53.5 hours / 4.5 hours	50
342	Ag-111	7.5 days	6
344	Eu-152	12 years	27
351	Bi-211	2.15 minutes	14
352	Pb-214	26.8 minutes	36
356	Ba-133	10.51 years	69
360	Se-83	25 minutes	69
362	Pd-103	17 days	0.06
363	Gd-159	18.0 hours	9
364	I-131	8.05 days	82
368	Ni-65	2.56 hours	4.5
388	Sr-87m	2.83 hours	80
393	Sn-113	115 days	64
393	In-133m	100 minutes	64
403	Kr-87	76 minutes	84
405	Pb-211	36.1 minutes	3.4
412	Au-198	2.698 days	95
427	Sb-125	2.7 years	31
439	Zn-69m	13.8 hours	95
Gamma Energy (KeV)	Nuclide	Half-Life	Percent Yield per decay
441	I-128	25.0 minutes	14
444	Hf-180m	5.5 hours	80
468	Ir-192	74.2 days	49
477	Be-7	53 days	10.3
479	W-187	23.9 hours	23
482	Hf-181	42.5 hours	81
487	La-140	40.22 hours	40
490	Cd-115	53.5 hours	10
496	Ba-131	12 days	48
497	Ru-103	39.6 days	88
511	Cu-64	12.8 hours	38
511	Ga-68	68.3 minutes	176
511	As-74	17.9 days	59
511.0034	Na-22	2.60 years	180
512	Ru-106 / Rh-106	367 days / 30 seconds	21
514	Sr-85	64 days	100
514	Kr-85	10.76 years	0.41
520	Se083	25 minutes	59
527	Xe-135m	15.6 minutes	80
530	I-133	21 hours	90
530	Cd-115	53.5 hours	26
533	Nd-147	11.1 days	13
537	Ba-140	12.8 days	34
538	I-130	12.4 hours	99
554	Br-82	35.34 hours	66
559	As-76	26.5 hours	43
564	Sb-122	67 hours	66
570	Bi-207	30 years	98
583	Tl-208	3.10 minutes	86
Gamma Energy (KeV)	Nuclide	Half-Life	Percent Yield per decay
596	As-74	17.9 days	61
599	Sb-125	2.7 years	24
603	Sb-125	60 days	97
605	Cs-134	2.05 years	98
609	Bi-214	19.7 minutes	47
619	Br-82	35.34 hours	41
622	Ru-106 / Rh-106	367 days / 30 seconds	11
637	I-131	8.05 days	6.8
658	Ag-110m	253 days	96
658	Ag-110	24.4 seconds	4.5
661.64	Cs-137 / Ba-137m	30 years / 2.55 minutes	85
669	I-130	12.4 hours	100
670	I-132	2.3 hours	144
686	W-187	23.9 hours	27
695	Pr-144	17.3 minutes	1.5
697	Te-129m	34 days	6
724	Zr-95	65 days	49
726	Ru-105	4.44 hours	48
727	Bi-212	60.6 minutes	7
740	Mo-99	67 hours	12
743	I-130	12.4 hours	87
747	Zr-97 / Nb-97m	17.0 hours / 60 seconds	92
748	Sr-91	9.67 hours	27
756	Zr-95	65 days	49
765	Nb-95	35 days	100
773	I-132	2.3 hours	89
Gamma Energy (KeV)	Nuclide	Half-Life	Percent Yield per decay
777	Br-82	35.34 hours	83
780	Te-131m	30 hours	60
796	Cs-134	2.05 years	99
810	Co-58	71.3 days	99
832	Pb-211	36.1 minutes	3.4
835	Ga-72	14.10 hours	96
834.827	Mn-54	303 days	100
837	Mn-56	2.58 hours	99
850	Te-131m	30 hours	31
879	Tb-160	72.1 days	31
885	Ag-110m	253 days	71
889	Sc-46	83.9 days	100
898	Rb-88	17.8 minutes	13
900	Pa-234	6.75 hours	70
935	Cd-115m	43 days	1.9
966	Tb-160	72.1 days	31
1020	Mo-101	14.6 minutes	25
1025	Sr-91	9.67 hours	30
1063	Bi-207	30 years	77
1078	Ba-68	68.3 minutes	3.5
1095	Fe-59	45 days	56
1115	Zn-65	245 days	49
1115	Ni-65	2.56 hours	16
1120	Sc-46	83.9 days	100
1120	Bi-214	19.7 minutes	17
1122	Ta-182	115 days	34
1140	I-135	6.7 hours	37
1173.2	Co-60	5.26 years	100
1210	Y-91	58.8 days	0.3
1274.5	Na-22	2.60 years	100
Gamma Energy (KeV)	Nuclide	Half-Life	Percent Yield per decay
1278	Eu-154	16 years	37
1280	I-135	6.7 hours	34
1292	Fe-59	45 days	44
1293	In-116m	54.0 minutes	80
1293	Ar-41	1.83 hours	99
1308	Ca-47	4.53 days	74
1332.5	Co-60	5.26 years	100
1350	Mg-28	21 hours	70
1369	Na-24	15.0 hours	100
1380	Ho-166	26.9 minutes	0.9
1408	Eu-152	12 years	22
1426	Cs-138	32.2 minutes	73
1434	V-52	3.76 minutes	100
1460	K-40	1.29 x 109 years	11
1481	Ni-65	2.56 hours	25
1524	K-42	12.4 hours	18
1570	Pr-142	19.2 hours	3.7
1596	La-140	40.22 hours	96
1600	Cl-38	37.3 minutes	38
1692	Sb-124	60 days	50
1764	Bi-214	19.7 minutes	17
1780	Al-28	2.31 minutes	100
1811	Mn-56	2.58 hours	29
2614	Tl-208	3.10 minutes	100
2754	Na-24	15.0 hours	100
6130	N-16	7.2 seconds	69
7110	N-16	7.2 seconds	5

By the way, another great place to creep around and find info like this is the Oak Ridge National Lab at http://web.ornl.gov/info/reports/ which has tons of DECLASSIFIED reports of various techniques for radioactive fun. The earlier reports (1940s) are much more useful--later reports deal with specific institutional issues at the lab.

The Oak Ridge directories are by year--so just poke around. A cool file I found was "The Preparation, Properties, and Uses of Americium - 241, Alpha-, Gamma-, and Neutron Sources" in the 1962 folder. It was in one these reports that I found the idea of using talc all over the inside of a detector to increase internal reflectance...but was abandoned in favor of wrapping the sides of the crystal with aluminum foil instead, 'cause you know: who the heck wants a bunch of talc all over the insides of their particle physics equipment right? Especially since they were blowing air into the detectors to keep a positive atmospheric pressure in them so they could use them under water...'cause then the talc would just blow out into the water right? And that would be a really odd mess right? Then again I almost blasted a metal rod through my eyeball during a mishap with some acetylene so who am I to judge.

Anyway, you can actually order radioisotopes and have them delivered straight from the source in Oak Ridge, Tennessee. From the "Home of the Atomic Bomb" came my Cesium-137 sample.

"What's in the box?" Ok Brad Pitt, I'll tell ya: Cesium-137 from the Oak Ridge Tennessee National Nuclear Lab. Yes, the place where the atomic bomb was made.

I already have a probe (a Ludlum 44-7) that can read at the 60 KeV to 100 KeV range, but it's a Geiger-Mueller (GM) tube and not a scintillation crystal. Also, that's spread out over the alpha, beta and gamma ranges. I do have a probe with a scintillation crystal though, but it's a Ludlum 42-2 set up for neutron detection. Also, apparently my own blog here is one of the few resources in the that probe's specifications. I have no idea how it would react to gamma wave-other than screaming wildly like it does around Uranium. Although, I turned it down (up?) to 600v and it's actually a really nice gamma detector at that range.

Another option are lutetium-yttrium orthosilicate (LYSO) scintillators. What's neat about them is that they are in themselves radioactive! This is called in the literature "internal scintillator radioactivity". The lutetium (LU-176) has a half life of over 3 billion years. As a check source for calibration it's a fantastically stable thing to have. The small LYSO crystals go for around $10 online, although a bigger crystal for use as an actual scintillation detector can go for $200. LYSO crystals are very robust and can take being handled by human hands in humid air. They are also very dense and good at stopping particles. I already have one as a sample radioactive source. My geiger probes won't pick up it's weak radiation-so it's no go for Geiger detectors; only for gamma spectrometry.

Another crystal scintillation type is NaI(TL); which is Sodium Iodide crystals doped with a little bit of deadly Thallium. This type of crystal, although fragile, has the highest light output. It is the crystal by which other scintillators are judged by in that respect. Remember, we're going for flashes of light as particles hit the crystal, and then measuring the frequency of that light. 

Scintillation crystals react differently to different wavelengths of light and their power. Luckily, once a scintillator is mated to a Multi Channel Analyzer (MCA) the hardware and software do all the work and a lovely x/y line pops up telling you what you have.

Above is the scintillator I ended up with at first and while it's fantastic for survey meter work I replaced it for gamma Spectrometry while dialing in my new system.

Here's info about it anyway: It's made by an American company confusingly named "Alpha Spectra Inc", but its for gamma. Identical units are also found labeled as Bicron Inc. The unit as a whole is an Alpha Spectra Inc. 5I5 X 12/1.12 5B Scintillation Detector. There is an "I" not a "1" in the name on the label and the meager online info, but you could also try 515x12/1.12 as well. It's 9.5" Long and 1.4" square and has a 3" long x 1" square St. Gobain NaI(TL) crystal. 

It has an Adit-brand B29B01W Photo Multiplier Tube (PMT) with an 11 stage dynode. The "1.12" in the name apparently refers to the 1 1/8" diameter of the PMT. I've read where the 5I5 x 12 part of the name refers to 0.25" or 1.25" square crystal or something, but I don't see how that relates to the case or the crystal. I guess 0.515mm = 0.2" and 0.2" x 12 = 0.24". I dunno...but it was made in Texas. It's actually a version of their B29B02H that's just shorter, which is weird because the unit as a whole is super heavy and quite large already! It also features a delicious soda-lime glass window for the photons to enter.

It should be noted that D11 goes to Pin 12 (not pin 11). Anode = pin 13 and Cathode = pin 14. The 4700 cap is orange and huge and obvious, and ties D11 to ground. I believe the 5M resistor at the bottom is actually the potentiometer knob which can vary the total resistance of this unit from 11.4M to 16.4M Ohms. People who've actually managed to use this detector successfully for gamma spectrometry work actually turn it down to 11M ohms. 

The GS-1100A PMT driver has it's lowest voltage at 600v. See below for those calculations.

The Alpha Spectra Inc. detector has a sodium iodide crystal doped with Thallium NaI(TL) that shoots off photons when hit with gamma rays (which are also photons). Then a voltage multiplier dynode scales up the photons by x 1 million and turns them into electrons, then voltage which gives the readout. 

The spec sheet on the PMT seems to imply that it's happiest at 700v, but at onl 500 volts  it can "see through" my galvanized steel containment vessel to find the pitchblende (uranium) inside. Which is why preparations for the casting of a 223lbs lead "pig" vessel are under way. 

INFORMATION FOR GAMMA SPECTROMETRY

For gamma ray spectroscopy NaI(TL) crystal scintillation detectors are best. Bicron, Rexon, Teledyne and a few other detector brands can share internal components with each other. Here are general crystal stats:

Type	Scintillation Crystal Type	Density (g/cm)	Emission Maximum (nm)	Decay Constant		Index of refraction	Relative conversion efficiency
BaF2	Barium Fluoride	4.88	310	0.63		us	1.50
BGO	Bismuth Germanate	7.13	480	0.3	us	2.15	15-20
CaF2 (Eu)	Calcium Fluoride	3.18	435	0.94	us	1.47	50
CdWO4	Cadmium Tungstate	7.90	470/540	20/5	us	2.30	25-30
CsI(Na)	Cesium Iodide doped with Sodium	4.51	420	0.63	us	1.84	85
CsI(Tl)	Cesium Iodide doped with Thallium	4.51	550	1.0	us	1.79	45
CsF	Cesium Fluoride	4.64	390	3.5	ns	1.48	5-7
GSO(Ce)	Gadolinium Silicate doped with Cerium	6.71	440	30-60	ns	1.85	20-25
LiI (Eu)	Lithium Iodide	4.08	470	1.4	us	1.96	35
NaI (T1)	*Sodium Iodide doped with Thallium*	3.67	415	0.23	us	1.85	*100*
YAP	Yttrium Aluminum Oxide Perovskite		350	27	ns
ZnS(Ag)	Silver activated Zinc Sulfide	4.09	450	110	ns	2.36	25 - 30

Rexon Inc.'s Dr M. H. Farukhi has layed out an informative explanation of each crystal type here: http://www.rexon.com/crystalscintypes.htm

Many different detectors are made by the same few companies. A $600 Bicron unit can be identical to a $40 used Rexon!

Also I discovered that my Rexon 3.0 PX 2.0/3.0 is also known as an Alpha Spectra 128i/3 and as a Bechtel 223-128. It has a super fancy voltage divider with three tiers of round circuit boards-which unplugged and replaced with the one from Iradinc.

The bottom layer is high voltage. The other two are controls for computer interface.

Luckily, it just unplugged easily and I popped on my new 62M Ohm voltage divider and then it worked with the Ludlum Model 3 survey meter and the GS-1100A.

GS-1100A PMT DRIVER

The PMT (photo multiplier tube) driver from Australia can apply voltages from 600v-1100v so I may have to short the first zener diode to ground (inside the GS-1100A driver from Australia, not my PMT). That will drop the voltage down -200v from the minimum 600v; so I'll be at 400v. We'll see. The PMT driver also plays best with detectors that have a resistance of 15M Ohm. 

The Alpha Spectra Inc. has a variable resistance pot right on top that can vary the resistance from 11.4M-16.4M (according to spec sheet) so I should be fine but again, we'll see. I had to turn this pot all the way down and then turn the voltage on my Ludlum 3 survey meter down 495 v to get the background reading to just a few counts and make it usable as a simple gamma probe. Of course this may not matter in gamma spectrometry and maybe being in my custom cast lead enclosure should help a bit. Maybe I can also simply swap-out the potentiometer with one of a different resistance?

Looking at the face value of the resistors it's actually 11.181M + the 5M potentiometer. So, 16.181M working with at most 500v.

The GS-1100A has a known voltage dip which may help me out too. It has a 1M resistor built into it, which is used in the following calculations as "+ 1M".

Voltage Setting on the knob = (desired voltage/Actual Resistance) x (Actual Resistance + 1M)

400v / 16.181 x (16.181+1) = 424v on the knob

The lowest knob setting is 600 volts (which is actually 400 volts if I opened the unit up and grounded the 1st Zener Diode). That lowest setting of 400 volts would be less than 400 volts as you can see from the maths above with my particular detector plugged in the actual power reaching the PMT is only 94.11%. 

So at the lowest setting of 600 volts > ground shorted to 400 volts =  376.44 Volts actual!

Not bad. I can always turn the voltage up, and this is before the lead shielding and shutting off the fluorescent lights dangling 2 feet above my testing table to get the background noise as low as possible.

Of course my neutron probe with a ZnS(Ag) crystal might work too --and it can take 600v no problem. So I've got plenty of options to try if just plugging in the Alpha Spectra Inc. detector at 600v is too noisy.

A "noisy" background with a lot of clicks on a survey meter might mean nothing on a spectrometry setup; and even though there were lots of clicks, I could still use the 10x, 100x meter settings and the needle was at the 1/4 to 1/2 point (with no radioactive sample) and rose noticeably when a radioactive sample was brought close to it: so plenty of headroom! Luckily the Ludlum 3 survey meter has an audio off switch, so the constant background clicks couldn't bother me.

Also, I noticed that the meter started rising when the sample was more than 2' away! None of my other detectors do that, so we've also got plenty of sensitivity! The fact that I was holding it in my hand was none too pleasant a thought.

I shouldn't be surprised, in a November 1950 Status and Progress Report from the Oak Ridge National Lab:

With a thallium activated NaI crystal, the lower energy detection limit is of the order of 10-15 Kv. The instrument has been used successfully in finding 25 gms. of U 235 deliberately hidden in a location where the background is of the order of 5000 counts per minute. The 25 gram source was easily detectable from one foot away even through 1/2 inch of steel; without shielding it read 30% over background at 10 feet.

I guess I need to move to a spot farther away from my isotope collection!

Scintillator detectors (as opposed to Geiger-Mueller tubes) are also notoriously sensitive to electromagnetic field (EMF) interference from lights and other devices. The lead (and possibly a sheet of copper or mu-metal) will help with that too! 

My next tests were: using a proper 10M ohm input sensitivity voltmeter instead of an 11M one; putting the Alpha Spectra Inc. scintillator in a light-proof bag to test for light leaks; turn off the lights to test for interference from the fluorescent lighting in my lab. 

Test results: no light leak; no significant EMF interference. multimeter with 10M Ohm input resistance reads about 500v (instead of 250v). 

The Alpha Spectra Inc. detector seems to operate just fine with the GS-1100A unit using PRA and/or Theremino MCA. I've have it at 600v-1000v and am still trying to find the sweet spot. At the lower voltages I have to raise the input gain in PRA to 3 or 4. I can have gain set to 1 with the voltages higher. It'll take weeks of experimenting to determine which settings have the best singal to noise ratio; however they all seem to work fine.

Do you want to learn more about photo multiplier tubes? Noted manufacturer Hamamatsu has this free book available as a 323 page PDF file online: https://www.hamamatsu.com/resources/pdf/etd/PMT_handbook_v3aE.pdf 

Adit themselves are now part of ET Enterprises: http://www.et-enterprises.com/ and you can search this tube and get spec sheets and even accessory part numbers.



Next steps will be making the lead shielding "pig" and setting up the hardware.

Gamma Spectrometry Lab 2: The Lead Shield 

THE LEAD PIG

The lead was delivered yesterday and actual fancy blueprints drawn up. Soon a piece of equipment (the GS-1100A) will arrive from Australia: instead of clicks I'll have a computer screen saying "Uranium detected". Background radiation is an issue because instead of just a few extra spikes we'll get too many spectrum lines--this isn't a real problem since both PRA and Theremino allow you to take a reading of the background and then delete it before you place your radioactive sample onto the detector.

So a lead shield was needed. The design started simple and lead is cheap. 

I requested a large lead shield since I could then also use it for cosmic ray and muon detection where you want the least amount of background noise as possible.  

So, a mold was made to pour the lead into.

At the bottom is a flat lid of a large "bowl". 

On top of that is bolted a column of small 4" diameter Turkish coffee cans (the "pipe" in the diagram above). These will be empty and provide the open center of the lead pipe we're making. Of course, to have one end of the pipe sealed permanently we'll pour 2" of lead into this center column-the rest of the lead gets poured outside of this column.

The surrounding the central column is a metal sheet pounded into a perfectly straight cylinder that is 8" in diameter. 

The rest of the lead gets poured outside of the central column and inside of the outer column. This yields a lead pipe with: a 4" diameter center opening inside diameter; an 8" exterior diameter and 2" thick walls. With 2" of lead closing off one end of the pipe permanently.

Here is the start of the 8" outer cylinder mold being formed. It started as a rectangle sheet of steel. Each of the two ends were bent to form a simple interlocking joint (a flatlock seam) once the sheet was formed into a cylinder. The bends were made with a tool called a seamer but pliers could have been used.

A weight lifting weight was placed inside the cylinder and a hammer used to crimp each end of the cylinder to act as a sort of mandrel to pound against. The weight was used at both ends of the cylinder to true up and round the ends-then this weight was removed. This provided a few things: the rounded edges look really nice; the rounded (somewhat chamfered / bull nosed / beveled) edge will provide a rounded edge to the lead instead of crumbly sharp edge; by pounding the edges of the cylinder over the opening at each end became a nearly perfect circle; this rounded edge is much stronger and keeps the cylinder from flexing; these edges are perpendicular to the cylinder walls which makes the cylinder stand perfectly upright on a table--which means it'll stand upright on the pot lid which will hold these molds while the molten lead is poured.

Here's the cylinder at the beginning of the process: it's locked together with the flatlock seam, but it's more of a teardrop shaped tube instead of a circular tube. The ends are locked together (loosely) at that seam. The seam is later pounded flat.

Patio blocks and steel bedframe rails.

Acetylene torch-propane is just too slow. 

Notice the sand at the bottom. After the center was filled with 2" of lead (for the end cap) sand was placed to seal the outer edge so the outside of the pipe could be poured.

The iridescent rainbow color is from tin contamination. Tin floats on top of the silvery molten lead and looks like bright blue plastic. 

After the first 2" the center column gets filled with sand to keep the lead out. Here you can see the area beyond the outer rim filled with white sand to keep the lead from spreading past the (black) outer casing of the pig.



Our Lead Casting Process:

1. Put lead wheel weights into crucible.

2. Heat from above and add more lead. 

3. Heat from below while someone else picks out the steel clips with a strainer ladle (big spoon with holes in it).

3. Take away the torch once all the solid junk has been removed.

4. Dip a large wax candle into the molten lead and quickly remove it: it will smoke and then burst into flames.

5. Strain any remaining slag the wax brought to the surface. 

6. Pour the lead into the mold. 

The wax candle flux helps break the surface tension formed by the intense heat oxidizing impurities in the lead (tin, zinc, etc.). Whatever doesn’t “reduce” back into molten metal gets quickly skimmed off the top with the ladle and then molten lead is poured into the mold. The result is a more homogeneous lead mixture and less lumps or crumbly bits in the finished product. 

Alternatively, burnt sawdust or straight-out carbon could be used. The carbon is better at reducing zinc and other various impurities than wax. Goodness knows I sure have enough carbon laying around: http://michaellogusz.blogspot.com/2015/08/great-balls-of-carbon-theyre-actually.html 

Supplies Needed:

• At least two buckets of wheel weights, or enough lead by weight (not including wheel clips) to fill your mold.

• Sand to keep lead from filling certain parts of the mold or leaking past the mold.

• Long 3/4" thick wax candle.

• Gloves (thick welder's gloves to hold the torch and for pouring crucible out.).

• Face mask (a full woodworker type plastic mask will help keep the noxious fumes out of your eyes)

• Blocks (concrete, cinder, bricks-it just has to be stable and fire-resistant).

• Bed rails (or something fire-resistant to hold the crucible).

• Ladle with holes (for picking out the steel clips and straining the slag).

• Coffee can for slag (have it near the lead, fill it and empty it occasionally onto the trays).

• Trays or place to dump coffee can of slag out repeatedly.

• Acetylene torch (propane works for casting bullets but not for melting 200lbs of lead).

• Vice grips to help hold crucible when pouring (pliers would slip, remove vice grips after each pour).

• Tiny shovel, broom, dust pan, funnel (to place the sand and then clean up).

Set all this stuff up before starting!!!!! Do a "walk-through" of how to position the torch, how to transition from heating top to bottom without hitting the knobs on the torch, who will ladle the slag and how you'll not burn their hands while they do it. 


Casting the Pig! It was finished on Thanksgiving 2016 so it's the Lead Turkey!

Here are the 10-15lbs of clips and slag removed from the first 100lbs of wheel weights' worth of lead. This was once an over-full 5 gallon bucket of wheel weights.

If you buy lead ingots you just get lead. If you buy wheel weights you get 10-35lbs of clips and other junk that gets strained out with the ladle. Remember that when pricing out lead sources!

This is the halfway point. About 100-120lbs of lead have been melted and poured into the mold. Look at those two trays filled with steel clips and slag! That's why you need two people: one just operates the torch--the other strains the clips and slag and then carefully pours the molten lead into the mold.


Blueprints showing the half-way filled status:

The lead turkey on its very own torpedo sled! ( and I know a little something about torpedoes: http://mikelogusz.blogspot.com/ )

Too smokey and too loud!

Gamma Spectrometry 3: Software

PRA / THEREMINO SETTINGS

I keep bouncing between using the PRA software and the Theremino software. With either you have to go into your computer's control panel > sound > recording > mic or line input properties:

Under the LEVELS TAB > set volume to 100%
Under the ENHANCEMENTS TAB > CHECK to disable all sound effects
Under the ADVANCED TAB > note your bits (16) and Megahertz (44,000 or 48,000 or 96,000)

In either PRA or Theremino you'll tell it that you're using your soundcard, that it's set to 16 bits and 96,000Mhz or whatever. You'll also have to specify you're using the LEFT channel in and out! 

Here are some recommended basic settings for PRA but you'll still have to play with the single input wave audio display with the x/y grid which is super-critical and a total pain:

These settings will change depending on your: scintillator detector; voltage setting on the PMT driver; type of sound card; volume setting of sound card; radioactive source; background radiation; type of experiment you're performing; etc. The above is the recommended starting points. 

In some versions of the software, depending on your detector you may have negative pulses. You'll just type in "-0.3" instead of "0.3" in the top left Height Threshold windows. 

I played with different Height Threshold settings from 0.01 to 1 and everything still "worked" but the readings were different. So, basically as long as you have the input = Left and output = Left and Channel Selection = LEFT in the PRA or Theremino software and the volume set to 100% on your control panel > soundcard you'll almost always get some sort of reaction by moving radioactive material up to the detector.

After that, it's just calibration to fine tune your settings. For me, getting a response on screen was easy. I'm still playing around with the calibration. 

A word of warning: Am-241 has TONS of gamma radiation. Online, many many people write that it's "mostly" or "almost all" alpha radiation, but they are WRONG! While alpha radiation of Am-241 is it's primary decay, a piece of Am-241 out of a smoke detector puts out a LOT of dangerous gamma radiation. Many times people on the internet confuse the (true) statement that "AM-241 decays to NP-237 by 100% alpha emission"...which means just that, the rest of the Am-241 that doesn't turn into Np-237 turns into gamma rays--which is a really weird way of phrasing that, but when everyone else is just cutting and pasting the confusion grows. Thus you have alpha and gamma radiation.

I tend not to cut and paste words from other people-I write what I see and do, and with ALL of my half-dozen different radiation detectors I find a LOT of gamma coming off my numerous Am-241 sources. The internet is an echo chamber, and if someone gets something wrong--well, they're will be a ton of other people repeating that mistake.

When I place a sheet of cardboard between the AM-241 and a detector the count rate goes down, but not away completely. AM-241 can make my gamma detector (which cannot register alpha radiation at all) squeal. Experiment for yourself and see. 
Anyway, Am-241 will show up as Am-241, Np-237, Uranium, Protactinium, Thorium, Actinium, Radium, Thallium, a few radioactive versions of lead...it's kind of a mess on a spectroscope. You can get rid of the first four spikes by using a Thorium source like a welding electrode (incorrectly referred to as welding rod) instead of an Am-241 source.

So, to simplify calibration I purchased a CS-137 check source. 

Cs-137 beta decays into Ba-137m (metastable). The Ba-137m gamma decays (at 661.64Kev) into stable Ba-137. This gives us the right hand spike on screen. In the center may be a little spike at 551Kev because 

Hopefully, once everything is setup properly the screen will show a large spike at 661.64KeV (which is really from the Ba-137m decaying into stable Ba-137) and another Barium spike closer to 32KeV. This is much simpler to deal with at first: two spikes on your computer screen.

As an aside, you can drizzle NaCl onto Cs-137 and elute the radioactive Ba-137m into a liquid solution that is radioactive! This is how those radioisotope generators with the little syringe plungers at school work. Wait an hour and more Cs-137 will decay into Ba-137m, and you can re-wash it with the acid to get even more radioisotopes out.

In these software programs when you do a background calibration there are two different ways: start taking data to teach the program what the individual scintillations look like (with the radioactive sample placed at the detector) or left clicking the computer mouse while using BGO on/off (with NO radioactive sample anywhere near the detector).

One teaches the program what the target isotope radiation (which you are measuring) looks like, the other teaches it what the background cosmic radiation (to be ignored) looks like. If you confuse the two you'll never get your setup calibrated correctly.

An important part in Theremino is "tuning" the waveform in the "Pulse Shape Visualizer" window! Not much is made of it in the manual, but in online tutorial videos it appears to be the key to getting anywhere.


Another thing is time! I would get a spike where I should but everything seemed messy and not really convincing. Then I decided to let it run for a few hours and bingo: much more professional results in PRA. In Theremino I got very similar (and perhaps a tad better) results in minutes--but only after weeks of fiddling with various detectors and finally replacing the old 5M Ohm voltage divider ((below) end caps with a 62M Ohm one from Irad Inc. This gave the added benefit that my new Bicron detector would also would now with my Ludlum 3 survey meter. The Alpha Spectra Inc. worked with the Ludlum 3 already because it has a variable Ohm load up to 16M.

Here is the new 62M Ohm voltage divider. It has a BNC connector. The old one had an MHV (mini high voltage) connector that worked with BNC cables once you trim the protruding white insulation off the MHV connector. Coincidentally, this is why SHV (safe high voltage) connectors were invented: you can't accidentally or on purpose force them to work with lower voltage BNC connectors.

P.S. Here's the internet's only photo (as of 3/7/2018) of a "Keplertron" which is a low-energy beta Spectrometer:

Don't worry-this was suitably declassified before posting ;)


Mike

Extreme Contact Explosive Nitrogen Triiodide

Extreme Contact Explosive Nitrogen Triiodide

I just synthesized the what is considered by experts to be the most unstable explosive in the world: Nitrogen Triiodide!

It's like those whipper snapper crystals wrapped in tiny tissue paper balls that you drop and they explode, only these explode if you blow on them. They're so unstable you can't even pick they up, let alone wrap them in tissue.

It was really easy too!

1. Drop some iodine crystals in some clear ammonia. The ammonia has to say "clear" on the bottle. The other stuff has soap in it.

2. Let them soak for 15 minutes. At this point they're less explosive, but they still might detonate.

3. Pour out the crystals on some paper towel to dry. The drier they are, the more unstable they get.

After an hour I barely touched the paper towel and all the crystals exploded! The explosion of 5 tiny crystals was louder than a cap gun but slightly quieter than a firecracker. I was sort of expecting it, so it was fun and not scary.

Super easy huh?

Here are some random notes about this quick project:

This is a project you only do once. Get the cheapest, smallest bottle of iodine crystals you can. You'll use a tiny amount and the rest will just sit on a shelf since this stuff is so uselessly unstable. This bottle was $20 on Amazon.

The iodine crystals are a lead grey color. They instantly start vaporizing and staining whatever they touch. Note the yellow discoloration on the white paper: they pellets were poured out and photographed in about 5 seconds, but that was long enough to stain.

If these crystals touch fabric they instantly start staining reddish-orange. I was able to quickly scrub it off with water and a remaining stain seemed to evaporate! Iodine will stain your skin for weeks like a henna tattoo. Supposedly sodium thiosulphate will help remove stains. Sodium thiosulphate is also used in anti-fungal footbaths and as an antidote for cyanide poisoning!

This is a standard red party drink cup. Note the TINY amount of crystals soaking the ammonia at the bottom of the cup. This is enough for a LOUD explosion. You'll probably make this little bit once and never make this again: it's that fantastically unstable! They instantly turn black once in contact with the ammonia.

Crystals with hand for scale. Note the yellow staining on the paper.

Here they are...waiting to explode. If you leave them alone they explode on their own. When they go off they splatter brownish-purple staining smoke everywhere: yet another reason you'll probably only play with this once.

Nitrogen Triiodide is so unstable you can set it off with alpha radiation! Just point some AM-241 radioisotope at it and it goes off. It's so unstable that it took scientists 180 years to finally get a good look at its molecular structure (1990 by Tornieporth-Oetting and Klapötke) and even then they had to synthesize it using a boron mono fluoride ultra low temperature sublimation process to produce a red version that wouldn't explode in their spectrometer!

Anyway, this was a fun after-work diversion while I spec out my new gamma spectrometry laboratory setup.

All the party cups exploded and I'm squishing myself under here until the noise stops! I'll flatten myself under the blast zone Meow.

The party cups exploded, but the plates of salmon seem stable. Yum!

Homemade X-Rays From A Vacuum Tube

Homemade X-Rays From A Vacuum Tube

In the electromagnetic spectrum, X-rays are between ultraviolet and gamma waves, but there is some overlap between the x-rays and gamma waves. Simply speaking, the difference between X-rays and gamma rays is that: 

Gamma radiation is produced by nuclear decay of radioactive atoms.

X-rays are produced by electrons banging into metal.

Except for their source, there is basically no defined difference between the two. They're just photons, like all electromagnetic phenomena. Photons have no mass and no charge. They are light itself. I've played with gamma radiation already using my mineral collection. To experiment with x-rays I had to make them myself. So I did! 

How did I do it? Easy! 

I found an old vacuum tube with a metal cap on top.

I took a multimeter set to Ohms and touched the probes to each pin. The two pins that gave any reading were the heater pins.

I took the output wires from my high voltage source and connected one to the metal cap and the other to one of the heater pins.

Turn on the power to over 20, 000 volts and a purple glow inside the tube made my Geiger counter go wild! 

My power source was a $9 3.6v-6v to 400, 000 volt boost step up power module high voltage generator from Amazon. I could have fed it with two AA batteries, but i just used the Elenco power supply I built to give it 6v DC input.

The tube was $1 at a local antique shop. I have a bunch and only one produced a lot of x-rays. The first one in the video was actually the only other one to produce x_rays, although rather weakly.

Instead of a power source to power the step-up boost transformer, two AA batteries would work fine. I used it to give 0-6 volts DC input into the boost transformer at up to 1 amp. Then I used the 3 amp outputs and the purple glow inside the vacuum tube grew intense, but so did the internal sparks and noise so I don't recommend it.

Here is the setup:

Here's the spark gap without the vacuum tube in between the wires.

I have a photographic darkroom, so I'll eventually get around to x-raying things on top of film plates and developing them. 

About the metal cap at the top of my tubes:

The metal top cap connects to one of the electrodes, the other electrodes being connected to the tube’s base pins. There are a few uses for the metal top cap seen on some vacuum tubes: sometimes it’s used as the anode, which means it’s more robust and can handle higher voltage. They run the highest voltage through the metal cap so it’s isolated this way. 

They also do the exact opposite: sometimes a very low signal was sent through the metal cap for control grids. 

So, either the metal cap can be the HIGHEST most dangerous voltage-or the LOWEST safest voltage that you may actually need to test. 

It’s a real gamble. You might fry your meter or even get electrocuted. For my uses I ASSUME that the metal cap is the anode and blast it with high voltage to produce x-rays. I touch NOTHING and if the tube blows I don’t really care. In my case my meter makes no physical contact since it’s a Geiger counter. Back in the “good old days” you could tap your finger on the metal grid control cap and hear it on sound equipment…of course if that control cap turned out to be hooked to the anode you wouldn’t have a finger left. ZAP!

Above is a video of my newest tube: the infamous 2x2 which gives off massive amounts of x-rays. It doesn't seem this matter which pin I fed the high voltage to, the result was lots of x-rays.

Can't Delete Photos from Gallery in Android?

Can't Delete Photos from Gallery in Android?

Here's a quick rundown of what FINALLY worked!

Do have photos/albums showing up on your android phone or tablet that you can't delete? You click on them but "delete" doesn't show as an option like your other photos? Does the album have a little Picasa emblem (rainbow color wheel) instead of a folder emblem and have a name like "Auto Backup", "Blogger Pictures", "Profile Photos"?

Get onto a DESKTOP computer (mobile app version sometimes doesn't work) > login to your google account (or login to gmail) > click picasaweb.google.com/lh/myphotos?noredirect=1 and edit away!

If you have your devices synched to your google account (which is what causes these photos to show up) then you may have photos in: this Picasa web storage; google Drive, google photos app; on your device's main storage card; your devices add-on memory card; google+; etc.

If you delete photos from here they will be wiped out EVERYWHERE: from your synced phones, tablets, computers, your BLOGGER posts, google photo app, android gallery/photo gallery app, etc. So be careful!

This is what worked when unsyncing > clear gallery cache > turn sync back on = the photos disappearing for 5 minutes and then showing back up.

Here's that trick in case you want to try it:

Settings > Application Manager > ALL > Gallery > Clear Cache.

Settings > Accounts > Google > Tap on your gmail > uncheck what you don't want synced to all your devices (Picasa Web Albums).

You can leave sync off, but then your photos won't show up on all your devices. BETTER YET: click on the link at the start of this post and edit there from a DESKTOP computer that's logged into your gmail.

Another thing that can grab and save photos/data is: Settings > Personal > Backup and reset. On all my devices this is set to save info to "Google Servers". It's actually a great feature, but all these places can be the actual location of a certain photo you want to delete, in this case a photo of a cat.

After a week of trying the cat photo is GONE from about 8 different locations/devices: including google+ which the user never signed up for but was included in the "google account". If you have gmail, then you may have all sorts of google app accounts that you never actually signed up for-they're just tacked onto your gmail now.

WARNING:

Hope this helps someone else, but remember that deleting a photo ANYWHERE in google deletes it EVERYWHERE!

SUMMARY

Eventually they might show back up. Here's another route to take: delete the photos from the FOLDER that feeds the un-deletable Picasa albums. Get on a desktop computer > sign into google account > click picasaweb.google.com/lh/myphotos?noredirect=1 and delete the actual photos. It will give a huge list of the places that the photo is being deleted from! THEN go to settings > Accounts > Google > click on your gmail address which shows up > make sure "Sync Picasa Web Album" is CHECKED > click SYNC! THEN settings > Application Manager > ALL > Gallery > clear cache. If you don't they'll just eventually reappear. This way you can also KEEP your sync and backups going, just delete the individual photos you find annoying. This worked for a TON of my photos, but there is still one that keeps coming back, but that's better than the 305 that kept showing up!

You ain't gonna get rid of me that easy!

When I long press that 1 photo it doesn't show the details>location like the others so I have no idea where it is coming from...and yes, it's another cat photo.

Power Source From Computer Into a Bench Lab Supply

Power Source From Computer Into a Bench Lab Supply

Here's a quick and easy way to turn an old ATX computer power supply into a bench lab power supply.

Below is a typical power supply from a computer. Some power supplies require a load on them to operate. Some have enough of a load to operate with just the built-in fan running once you turn it on. For a supply that needs a load you'd have to add a resistor. My supply was purchased for $3 at a resale shop and doesn't need a resistor.

So, how can we get this power supply up and running when it's out of a computer? Easy! Just place a jumper wire from the 4th wire to a black wire. Usually the 4th wire is green. It will be the only green wire in the big plug. There will be many black wires. I chose to jump the green wire to the black wire that was to the right of it in position 3 from the right (with the little lock on the connector facing you).

With this setup my supply was able to turn on and its fan started running. Success! I did not need any resistors apparently. 

Theoretically I could have stopped here and just used the plug as a power output. But that wouldn't be much fun. So I kept going.

I unplugged the unit from the wall again and cut all the many connectors off. Cut as close to the connectors as possible to leave the wires longer.

I opened up the power supply at this point to see inside. BEWARE: the capacitors inside this (and any) device will stay charged for months until one of two things happens: either they are bled off by a resistor; or they shock and kill/harm you! 

A capacitor is very much like a battery. It holds energy. When you stick a battery up to a light bulb it will slowly discharge energy to light the bulb for hours. When you stick a capacitor up to a light bulb it will discharge all of its energy instantly: like a camera flashbulb or a stun gun. I wouldn't be doing this if I didn't know what a capacitor is and what they looked like. 

It always amazes me when people take out a flyback transformer from an old CRT television and then ask around as to the "pin-out" of which of the zillion connectors they need to do certain things. Duh! Just take a photo of the item in question before you rip it out of the device! I did this, but it's not really needed because everything on this power supply is color coded.

Here you can see that all the orange wires are +5 volts DC.

Here's a photo showing that the single blue wire is -12 volts and all the yellow wires are +12 volts.

This is the important one: the 4th wire which is usually green! Okay, as you can see the green wire is labeled "PS/ON" for "Power Supply ON". This is the other end of the green wire that we connector to a black wire for the unit to power on. Now you know why this had to be done. I could put an on/off switch between the green and black wire, but my supply already has an an on/off switch.

Here is a photo showing the black wires. They're labeled "GND" for ground / common.

So, when I cut the all the connectors off I took only one of the black wires and kept it tied to the green wire. All the other black wires will be used in a moment.

Loosely tie any black wire to the green wire.

All the colors get separated out and will joined together.

Pencil out a line or two for hole drilling (with the cover off the actual supply). Make sure that you don't end up putting the output holes right over the large heat sinks inside the unit or else the wires will be pinched on their way out of the unit. 

Okay. Here we are: all the wires (except 4) are exiting the unit. I could have stopped here and soldered all the different colors to themselves and used the supply.

bought some INSULATED binding posts. Actually they're banana plug females. Where they touch the case they are PLASTIC and the little metal rings that tighten them to the back of the metal casing doesn't make contact with the center connection of each jack. If you used a plug or post that has a metal thread that touches the metal case YOU WILL DESTROY YOUR SUPPLY AND BE SHOCKED/ELECTROCUTED. 

Shocked means that electricity traveled through part of your body. Electrocuted means to be executed via electricity. It's a subtle difference I suppose. This unit is capable of up to 35 Amps. Enough to destroy most multimeters if you tried to measure the amps without a high voltage divider probe. I thought, "hmmm...that's weird, let me try my cheap meter on its 10 Amp setting." The result was that the meter wires heated up instantly and I pulled it away. I was lucky, but forget about measuring the amps. I had no issues with the voltage measurements and my multimeter wires plugged into their normal sockes: the black common/ground and the normal red plug (not the 10 Amp red plug).

Here are the banana plugs installed. Much nicer than bare wires sticking out of the case.

Here are some power leads plugged into my power supply.

Here are the results with no load other than the multimeter and the internal fan going. I printed a copy and pasted it to the top of the unit.

A recap of what wires did what including the 4 wires that didn't get connected to banana outputs.

Yellow +12V

Blue -12V

Red +5V

White -5V

Orange 3.3V

Black Ground/Common

Purple +5V always on "SB" Stand By mode.

Green PS/ON

Grey +5 PG feedback "Power Good"

Okay, so one of the black wires was soldered to the green wire. All the rest of the black wires were soldered to the COM/GRD output.

The purple wire always has 5 volts running to it, even when the power switch is turned off on the supply. If the supply is plugged into the wall it has power. You can hook a red LED up to the wire and then you'll know when the power supply is plugged in but not turned on. I didn't want to waste a black wire for that setup.

The grey wire is the "Power Good" feedback wire. If the power supply is running properly this wire will give out 5 volts. You can hook this up to a green LED and then you'll know when the power supply's on/off switch is set to on and everything is functioning properly. Again, you'd have to pair it to a black wire, which I didn't feel like doing.

So, why didn't I just use one each of all the colors instead of bundling them all together with solder? The thicker the wire (or the more little wires soldered together) the more amps it can handle. They were there and it was fun so why not build it to withstand anything it can theoretically put out.



So there you have it. My project in a nutshell:

1. Jumper the green to black to see if it'll start up without adding resistors.
2. Cut the connectors off.
3. Bundle all the same colored wires together and solder them (all the reds together, etc.).
4. Solder the green to a black.
5. Cut and tuck away the grey and purple wires.


That's it really. The other steps were drilling holes and making it look pretty with the banana output connectors. Then testing voltages and labeling the outputs.

After that I just slapped a "Logusz Particle Physics Lab" sticker on it...because it was laying around.

The power supply hooked up to just a multimeter is very stable. The voltage changes just .01 volts over time. The -4.72 voltage changes to -4.71 volts and back repeatedly. Not bad, but then again this is a regulated power supply! 

A regulated power supply is designed to provide stable voltages. They can typically keep the voltage (or current) stable with a narrow range. They're perfect for delicate electronics such as computers.

This is also a switching power supply which means it flicks on and off to manage the power and stability issues. This makes it lightweight, which is good for carrying around and it consumes less input energy too.

I paid $3 for the power supply at Disabled American Vets (DAV), which is a resale shop just like the Salvation Army. The banana connectors were super expensive: a whole bag for $12. These were the cheapest insulated for use on metal boxes ones I could find at the time.

Uninsulated ones are around $4 for a few, but they're only for plastic cases: you'd die if you used them on a metal box like this. I had a bunch of Amazon points so I basically got theses free anyhow.

It was fun and thus worth it to me.

SUNKEE DC 3V to 7KV 7000V Boost Step-up Power Module High-voltage Generator

SUNKEE DC 3V to 7KV 7000V Boost Step-up Power Module High-voltage Generator

3.4V DC in 7000V DC out!

I have a huge, heavy neon sign transformer  (NST) that puts out 5000 volts (5kV) at 18 milliamps (0.018A) and this little box puts out a much scarier spark, although the this doesn't seem to travel through stiff wires so I couldn't make a mini Jacob's Ladder out of it (yet). I'm thinking that means it has very low amps...I haven't measured it yet (use a high voltage divider probe or else you'll wreck your multimeter).

One side has 2 white (or red) wires: those are your outputs. Mine has 2 white outputs.

The input side will have two DIFFERENT color wires (1 red and 1 white). You have to hook positive input to the red. Hook negative input to the white.

In my photo the tips of the output wires are exactly 1/4" apart. The input voltage was 3.3 volts DC. The spark was loud, blue and awesome! Very crackly like a stun gun in the movies. I built a demo fusor (and made the Plasma Club) yet this seems scarier!

You must input DC voltage. You probably shouldn't go over too high or so, although I did momentarily and got a huge spark. The specs say 3 volts. I needed 3.4 to get a steady spark. I'll update if I blow it up and I'll include the final voltage.

If you have the wires farther than 1/4" then either it won't spark or you'll crank up the voltage really high to get a spark: either way you might destroy this device.

If you apply voltage and don't provide an escape for it (a spark or powering something) you can destroy this unit. That's another danger of trying to make a bigger spark gap: you'll be powering this unit but if there's no spark you can destroy this unit apparently. I think that's what the advert means by "don't let the pressure build up" meaning to keep it under load.

For about the price of a single firework you can play with this. I haven't destroyed mine yet. It fills the room with ozone quickly (toy train / slot car smell).

Get a sturdy holder apparatus for the output wires so you don't die.

It came in a cute box, but no instructions other than to keep it away from static. I have a feeling that if you rubbed this on a static wool sweater you might kill yourself with it.

Not bad for $7 on Amazon!


So, besides making the world's tiniest Jacob's Ladder what else did I make with it? An alpha particle spark detector!

Yep, just dial down the input voltage until the sparks sputter out. Then I moved a piece of radioisotope AM-241 (Americium) close to the L-shaped wires. ZAP! The alpha particles get ionized between the 7000 volts of awesomeness.

Check out my previous posts on a bunch of other alpha particle spark detectors, ionizing radiation chambers, nuclear cloud chambers and general Geiger counters.

Another neat thing about the electric arcs generated by this setup is that it reads incredibly COLD on my infrared thermometer! I'm not sure why. Here is my current guess before researching:

Theory 1: the sparks create ozone gas. Ozone has low emissivity: it absorbs infrared radiation. Gases (and dusty conditions) also give false low reading for IR thermometers as well. They gaseous ozone doesn't let the infrared radiation travel to the thermometer: the result is an ultra cold reading.

This is similar to how the sky will look utterly black through infrared heat cameras.

Theory 2: it is known that electromagnetic waves in excess of 3 volts per meter at 90-360 MHz will interfere with IR thermometers. I've got 3.4 volts DC turning into 7000 volts of fast pulsing sparks.

Theory 3: maybe the emissivity of the sparks are similar to that of shiny metal: terribly low. Simple IR thermometers are set to .95 emissivity. Spray paint a piece of aluminum super velvet-black and it will approach 1.0 emissivity. Shine that aluminum with steel wool and it will drop to around 0.003 emissivity! Basically invisible to the IR thermometer.