HOW TO GET YOUR KEYBOARD TO LIGHT UP IN LINUX MINT
Okay, so Linux Mint uses the “Scroll Lock Key” for a lot of stuff. However, most keyboards that can light up for easier typing in the dark use the Scroll Lock Key to also turn the LED illumination on and off. Sometimes it will say “EL on/off” under the words “Scroll Lk”.
Obviously that sucks. Especially if you have an awesome keyboard like my Logisys one that glows blue. So you have to do some typing in the Terminal window in Linux to get your scroll lock key back. Although Linux has thrown me some curveballs in the past two days (Cinnamon constantly crashing until I downloaded MATE desktop and setting it as my default workspace, etc.) At least I don't have to see things like this every few days:
Okay, Terminal is that black square button with “>-“ on it. It opens up a black screen that is a lot like the old DOS programming window.
Whenever I write “Type:” you type whatever is written after that and then click your Enter key.
1.Click on the Terminal button to open Terminal
Here’s where it gets weird. I somehow didn’t have permissions for any of my home files. Yep, I did NOT own my own files somehow. You may or may not have this problem. This second step gives you permission to read and write to your own files. I didn’t realize this because I’ve only had Linux Mint on my computer for 2 days (yet, figuring this out I feel is quite impressive). If you do already have permissions throughout your home directory you can skip to step 5.
2.Type: Sudo
3.Enter your password
4.Type: Sudo chown –R mike : mike /home/mike
Make sure to change ‘mike’ to your user name and pay attention to where there are spaces!
This will run a bunch of files, giving you permission to read and write to them. It’ll only take a minute to go through. So, back to fixing the keyboard.
5.Type: xmodmap –pm
This will list a few things with numbered mod lines. Usually 3 has nothing next to it, it’s just a blank space next to the 3. So, we’ll use 3 as our Scroll Lock light button place. If you have a different number blank then use that number. Somewhere I think I read you can go up to 32 or 35. I dunno. Just make sure 3 is blank and then go to the next step.
6.Type: cd ~
That’s cd followed by a space and then the ~ tilde symbol that’s at the upper left corner of your keyboard.
7.Type: Echo >.Xmodmap “add mod3 = Scroll_Lock”
Yes, there is a space after echo, but not after the >, and yes it’s a capital X and there is an underscore between Scroll and Lock.
You may notice your keyboard is lit up now!
8.Type: exit
This will exit you from Sudo (an elevated super user admin thing)
9.Type: exit
Yes, you exit again to exit from the Terminal program itself.
Now, restart your computer and see if your keyboard illumination light turns on right after booting up.
On my keyboard, this doesn’t actually make the Scroll Lock button work as the on/off—but it does light up my keyboard and keeps it lighted.
Alternately you can go into terminal and type: xset led 3 which will turn your keyboard light on. You can shut off your keyboard light by typing: xset –led 3
The xset codes get erased on rebooting. But it’s a nice option.
Another option (which just wouldn't take at the root level for me at least) was Xmodmap -e 'add mod3 = Scroll_Lock' which possibly will let you toggle your keyboard lights off and on. You'd have to add it (using "echo") to the ROOT folder of Xmodmap (I think) so the code would look a bit different in front of the .Xmodmap part. At one point it worked for me, but then stopped working. I don't mind my keyboard lights on all the time, so I just went with the simpler version without the "-e" portion, as I described in the numbered steps above.
For my next trick I’ll cut the wires from the LED backlights and solder them to a toggle switch and a point somewhere on the keyboard’s circuit board with the proper voltage. Maybe at the USB cable? That would be too high voltage? I dunno. I’ll dig around in there at some point. I don’t mind the LED light on all the time, so I’m not too amped up about it.
That was so boring. Computer "Science" is boring. Meow!
ANOTHER GREAT LINUX MINT TIP
Minimizing / hiding Chromium or even Word files with the upper right ‘_’ minimize button makes them disappear forever. Clicking on the show desktop button only brings them back if you hide them that way…sometimes.
Click on ALT + TAB key and you’ll get a choice of all the hidden / minimized internet browsers and other things you’ve hidden and lost or forgot about. Nice!
By the way, for all of the above I’m using the MATE desktop of Linux Mint 17.3 Cinnamon!
Big deal. I can hide / unhide myself anytime I want to in this mini Coleman camping tent! Meow! ...Actually I'm not too great at zipping and unzipping it up by myself.
Well, I'll show you how in this post. Here is my Ludlum Model 3 Survey Meter (it's the boxy thing on the right).
The box is a survey meter. The tube-shaped detectors (on top of the box) can be Geiger-Mueller tubes (GM), or they can be plastic crystals joined to a photo multiplier tube (PMT). So technically it's only a "Geiger Counter" when I have my other detector plugged into it-not the PMT in the photo.
So, in the above photo are what I use to set voltages. Most radiation detectors use 900 volts DC. Some do not. My Ludlum 3 can be adjusted anywhere from 400vDC to 1500vDC! Most true Geiger-Mueller detector tubes take 900vDC. So, we are dealing with electricity at high voltages. Which is why I have a HUGE Cal Test CT2700 high voltage probe, which has a 1000 to 1 voltage divider. 40,000vDC goes in, but only 40vDC would past through to my Extech MN36 multimeter.
Compared to the little probes (extreme left of first photo) you can see this beast means business! It can take up to 40,000vDC and 28,000vAC and only pass through exactly 1/1000th of the voltage, so my multimeter doesn't burst into flames!
I'll be setting the Ludlum survey meter to 900vDC, which will read as 0.900vDC on my multimeter. This high voltage probe needs a multimeter with at least a 10M Ohm input resistance. The Extech MN36 has exactly 10 Mega Ohms input resistance and works great!
So, on the Ludlum Model 3 survey meter there is a metal plate on the top of the case that says "CAL". It is just held on by two screws.
Here it is after removal, showing the 5 adjustment pots (potentiometers) that are screwdriver adjustable. ONLY adjust the top one labeled "HV" for high voltage. Some people put take over the other 4 holes which are used for adjusting the multiples meter readouts. Adjusting those takes a pulser devices which feeds a signal to the meter-if you don't own a pulser, you should never mess with those other pots.
Here's the steps I use to set the required voltage:
1. Unplug the detector cable from the box.
2. Clip the ground clip of the high voltage probe to the detector tubes holding bracket.
3. Turn the survey meter on and set to "Battery".
4. Put the point of the high voltage probe into the center hole where the detector cable is normally plugged into.
5. With a screwdriver, adjust the HV pot until your multimeter reads 1/1000 of your desired setting (900v would display as 0.900v).
6. Once done turn off the survey meter and wait 2 minutes before reattaching the detector cable. You'll hear the high voltage system "power down" a little while after turning the survey meter off.
Cautions:
1. You can get a shock by touching the center hole where the detector cable plugs in.
2. You can get a shock touching the other end of the cable.
3. You can get shocked touching the (red) portion of the high voltage probe below the (black) handle.
4. High voltage stays for a couple minutes (or more) even after removing the batteries from the survey meter!
5. Wait a few minutes after shutting off the survey meter before attaching our detaching the cable and/or a detector.
6. If your multimeter isn't 10M Ohms, your readings will be way off.
How do you know what voltage you need to set your survey meter to? Well, it depends on what detector tubes you want to use. The photo below shows my Ludlum 44-7 alpha/beta/gamma probe which takes 900vDC.
To the right is my Ludlum 42-2 neutron probe (Ludlum 47-1502 neutron scintillator), which is happier with a bit less than 1000vDC, even though the specs call for 900vDC. The meter pegs out at full and the clicks turn into a scream at 900vDC, so I set it around 600vDC when plugging in the neutron probe; but it's a fine art. Sometimes I dial it in to over 1000vDC just to get an occasional click as background. It's touchy! IT SHOULD BE NOTED THAT AT THIS POINT IT'S ONLY DETECTING GAMMA...a Ludlum Model 12 meter would be able to handle neutron probes because it has a threshold knob.
Just yesterday I plugged it in and without using a voltage meter I played around until I could (just barely) discern a slight difference when placing and removing an AmBe (Americium Beryllium) neutron source. I have to believe most of the clicks were gamma radiation noise, but the most usable setting just happened to be 600vDC after removing the probe and checking the actual settings with the multimeter/high voltage probe. At that setting there was a huge rise in clicks when I placed a Uranium source (alpha/beta/gamma) next to it too...so I'm just reading gamma at the moment. At some point a pure alpha check source (Polonium) will be acquired for definitive testing. I don't do much with neutrons at the moment so it's not a pressing issue.
Specs? Luckily, Ludlum is still in business and they have PDF files of many of their old user manuals online for free.
However, for the neutron probe Ludlum had nothing, so I had to find other sources of information. Other people actually contacted Ludlum, and all they could get was a confirmation of the model number. I had to dig deeper than that:
Below is some great information on some older NEUTRON DETECTORS (as opposed to Geiger Counters) which you may find used online, which I also put in an older post about "My Radioactive Dime". I snagged most of this info from a 1973 report to the US Atomic Energy Commission by Alex Lorenz. If you want to read the full report, it's available as a PDF online by searching "Review of Neutron Detection Methods and Instruments".
That document has more information on each device, including the method of detection (i.e. chemical composition of scintillator crystal, etc.). It' a great document to consult if you're like many people and find just a part/tube/probe of one of these devices and want to use it with a different base/amplifier/etc.
You'll want to pay attention as to whether your Neutron detector sees fast or slow neutrons--that makes a difference in whether or not you need to use paraffin or other moderators or actually have to remove those barriers and moderators from your experiment. You don't want to slow down your neutrons with paraffin if your device can only see the fast ones and vice versa.
DEVICE RANGE VOLTAGE
Ludlum
Fast neutrons
900v
(Model 42-2)
Eberline
slow or fast neutrons
900-1200v
(Model SPA-2)
Ludlum
1/v for thermal neutrons
900v
(Model 42-1)
Kaman
thermal & fast —
120v
(Model A-300)
0-14 MeV
Ludlum
thermal - 12 MeV
900v
(Model 42-4)
IiUdium
thermal & fast neutrons
900v
(Model 42-5)
LND
thermal neutrons
?
(Series 900)
Ortec
?
?
(System 525)
Nuclear Instruments
Linear between
?
and Chemical Corp.
10^7 and 10^12 nv
(Model 3782)
Reuter Stokes Co
1 0^15 nv
?
Reuter Stokes Cd
5X 0 ^014 nv
?
Reuter Stokes Rh
10^15 nv
?
Reuter Stokes V
10^15 nv
?
Reuter Stokes
10^10 nv
1000-1400v
(RSN-337)
(thermal)
Ludlum
thermal and fast
500-2400v
(Model 15)
neutrons
Centronics
<7.5x10^10 nv
1000v
(Type D.C. 12)
Reuter Stokes
3x10^4 to 2.5x10^5
800-900v
(RSN-17A/326/
(thermal)
330/251/327)
Reuter Stokes
10^4 to 10^11
800v
(RSN-229A)
(thermal)
Reuter Stokes
10^4 to 10^11
800v
(HSN-234A-M1)
(thermal)
Reuter Stokes
10^3 to 10^10
(RSN-15A/304/
(thermal)
100-1000v
325/332/306)
Reuter Stokes
10^3 to 10^10
200-800v
(RSN-314A)
(thermal)
Reuter Stokes
10^8 to 10^14
20-150v
(RSN-186S-M2
(thermal)
and 316S-M5)
LND
3 decades
(Series 30771)
500v
LND
5 decades
200-800v
(Series 3077)
Thermal (U235)
or fast (U238)
(Series 3075)
Thermal
200-500v
(Series 3000,
Thermal
50-500v
Series 3050)
Centronics
9x10^3 to 9x10^7
250-500v
(PFC 16A)
Texas Nuclear
Thermal
800-1400v
(Series 9300
Texlium)
Eberline
Dose response from
1600-2000v
(PNR-4 and
thermal to 10 MeV
NRD-1)
Eberline
0.01-10^3 eV &
1300-1800v
(PNC-4)
0.2-18 MeV
Harshaw
Thermal
1700-3400v
(Model series
B3, B6, B12, B14)
Reuter Stokes
10^-3 to 10^-5
2500-3500v
(RSN-7A/7S/44/
Thermal
177S-M7/320-M2/
108S-MG)
N. Wood Model G
?
1100-2300v
Centronics
3.3x10^3 to 6x10^6
900-1100v
(Series 5EB/6)
Texas Nuclear Series 9300 Texlium
Thermal
800-1400v
LND
(Series 3000,
Thermal
50-500v
3050)
Centronics PFC 16A
9x10^3 to 9x10^7
250-500v
Centronics PFC 16B
10^11
200-400v
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 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.
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
Lemme know when all the neutrons are gone and it's safe to come out! Meow.
