Following is a little guide to using photomultiplier tubes in DIY scintillation probes.
Photomultipliers are vacuum tubes that convert light into electrons and multiply the resulting current up to millions of times. They are used to detect the minute flashes of light generated by scintillators, materials that convert gamma and x-rays into visible light.
How to use these tubes? There are some things you need to remember when working with PMTs.
I recently bought a Raspberry Pi to experiment with. The first things I did with it was connecting and reading out Maxim Integrated DS1820 one wire temperature sensor and the cheap Chinese DHT11 temperature / relative humidity sensor.
To connect the sensors, I soldered some female pin headers to a piece of PCB. For the one wire network I soldered a 4.7K resistor between Vcc on pin1 (3.3V) and GPIO4 on pin 7. GPIO4 is the data pin for one wire, I used GPIO2 as the data pin for the DHT11. DHT11 “modules” with a PCB and three pins have their own pull up resistor, the separate 4 pin sensors don’t. Shown below is the quick setup, I soldered the DS1820 directly to the PCB, and connected the DHT11 with some wires for 3.3V, data and ground.
GPIO pinouts differ between the Raspberry Pi versions, I found the following pinout to be correct for my Raspberry Pi, a model A version 2.
Reading out the sensors is easy. For the DS1820, load the required kernel modules which are included in the Raspbian Linux distribution: Continue reading Post ID 1233
I recently bought a Ludlum Measurements model 2A survey meter on eBay from Obtanium. This is a nice meter which features the well known rugged Ludlum design, adjustable HV and 3 ranges of 500, 5000 and 50000 counts per minute.
Using a scintillation probe the meter easily saturates on the 500 cpm scale, and the 5k and 50k ranges are also overloaded with certain sources.
So I thought of adding a 500k cpm range. I already read the manuals and associated schematics to find out how to do this.
Ludlum model 2 and 3 offer about the same functionality and basically share the same PCB, circuit, knobs and switches. Depending on age and model there are certain differences, but a lot of the stuff and functionality is the same. Continue reading Post ID 1233
So, I got me a new Samsung phone because my old phone, a HTC Wildfire is rather slow, especially when it comes to websurfing. It also has low crap resolution. I am much happier with the new phone. So, what to do with the old phone? It’s still a small computer with a camera and touchscreen that should be doing something instead of gathering dust in a drawer.
One of the things I thought of was a webcam for my turtle tank. It currently houses two (I think female) red cheeked mud turtles, kinosternon cruentatum. I wanted to observe how often one of turtles gets out of the water to bask and what the general activity in the tank is.
I rooted the phone since I thought it would be handy to have root anyway and installed Cyanogenmod V7, an alternative Android version. This custom ROM does not include the Google Play store to install stuff on Google Play so I had to manually flash it. I am quite unexperienced rooting Android phones and installing custom software but I got it working eventually.
Next I installed IP Webcam, a nice free webcam app. Since it has a webinterface for remote access it is easily accessible with any computer. Being http-based it’s very easy to grab the images over the wireless LAN that the phone is on using a bash script:
#!/bin/sh wget http://192.168.64.4:8080/shot.jpg FILEDATE=$(date) montage -geometry +0+0 -background white -label "$FILEDATE" ~/shot.jpg /var/www/meuk/schildpadcam.jpg mv ~/shot.jpg /storage/plaatjesenfotoos/schildpadcam_arch/"$(date +%d%m%y%H%M)".jpg
This script uses wget to fetch the most recent video frame (the app is capturing video all the time), uses the imagemagick tool montage to visually timestamp the image and outputs a new picture in a publicly accessible folder on my server. Finally, the most recently downloaded picture is renamed with a timestamp in the filename and moved to a archive directory on the server. Continue reading Post ID 1233
Below are some interesting links about radiation (detection) that I have collected over time:
Have questions about geiger counters, the CDV-700 or gammaspectrometry? Just go to these Yahoo groups:
GeigerCounterEnthusiasts : PAGE 2…for Archives go to PAGE1
GammaSpectrometry : Gamma Spectrometry
Want videos? Check out these awesome Youtube channels:
http://www.youtube.com/user/antiprotons?feature=watch
http://www.youtube.com/user/antiprotons?feature=watch
Want pictures? Check out the Flickr Radioactivity pool: Continue reading Post ID 1233
