The cool thing about the app is that all tables are stored locally on phone (this is why it needs access to USB memory), so no network access is necessary - useful if you want to look up stopping power while working in a shielded area with no network.
In summary the features are:
ICRU 49 and ICRU 73 (revised version) electronic stopping power tables
BETHE_EXT00, a generic algorithm as used in SHIELD-HIT12A. Applicable for any ion to all 278 ICRU compounds (beware, use with care, can be off at lower energies), .
no network access needed after installation
calculation of CSDA range of particle in target material
inverse CSDA lookups possible (if you need to figure out what specific energy is needed to produce a certain range in a material.
Disclaimer: of course we do not claim correct reproduction of any of the data, use at own responsibility!
Thanks to:
Casper Christensen (programming this app)
Jesper Rosholm Tørresø (being Casper's supervisor and our contact person to the engineering school)
Jakob Toftegaard (writing most of the libdEdx backend and dedx.au.dk webpage)
I recently bought a cheap personal dosimeter by the Ukrainian company SOEKS. The best time to buy these is, when there has *not* recently been a nuclear disaster - prices are more reasonable then. I went for their "Defender" model, since it is capable of measuring accumulated dose, and I do not need fast counting provided by those devices with two GM-tubes.
Ok, I said "dose", but in fact I am not sure what it measures, it should be the operational quantity "personal dose equivalent", but it could also be something completely different (see ICRP 103). In fact I would not be surprised if they do some sort of "dose equivalent" calibration following ICRP 26 protocol from 1971. Many still confuse this.). Just for now, I'll just call it "dose", well knowingly that this is wrong.
It is the first time I order stuff from Ukraine, but shipment was really professional. They even email you a picture of your parcel with your address on, before they ship it. Contrary to some of the reports, I had no trouble with customs either. It was directly delivered to my institute address with no fuzz. Good thing!
Unboxing it, I found a nifty small gadget, which fits in a pocket, It comes with rechargeable AAA batteries (SOEKS brand, these people are really dedicated!), which can be recharged via the USB connector. I might have preferred AA batteries, as these simply perform much better than AAAs. But still, nice that you can always switch to normal batteries if you are in the field, run out of power and have no time to recharge.
One thing I really miss though, is a loop for attaching a lanyard. :-/
Switching it on, I immediately measured the normal background radiation levels here in Aarhus, around 0.12 µSv/hour.
One of the first things I tried out, was to take it along a trip to Turkey (yeah, the NUFRA2013 conference), to see what dose I'd receive during the flight.
I left it turned on while my cabin luggage was X-rayed. I did this three times, and each of these measurements gave 0.8 µSv.
On board the airplane I could measure a background level of roughly 2 µSv/hour, triggering the "Dangerous radiation" warning of the dosimeter. The threshold for the warning can be adjusted by the user. The 2 µSv/hour is probably a very conservative measurement anyway, as the device does not count the contribution from neutrons.
Video documentation of that flight (at roughly 10 km altitude):
Dose rate increased rapidly when we came above 8 km altitude. Under 8 km, it was pretty much just the background radiation. For the 4-5 hour trip from Antalya to Amsterdam I measured a total dose of 8.19 µSv. (This is 10 times the amount my luggage received when it was X-rayed. Very interesting.)
Arrived at Shiphol, Amsterdam from Antalya. Flight time 4 hours 47 minutes. Accumulated dose 8.19 µSv.
At our institute I can test the dosimeter at several sources. None of them are calibrated in any way, it is merely to see some signal. The strongest sources we have at the institute are couple of Americium-Beryllium sources for neutron generation. Whenever you have neutron fields you also have plenty of gammas, and if the sources is packed in a hydrogen rich moderator material there are also energetic protons (recoiling hydrogen nuclei).
The AmBe source sown below is locked up in a safe, but even when the safe is closed, you can see an elevated photon background in a meters distance:
Elevated background radiation near the neutron cabinet.
Inside the safe, the AmBe source is located in a paraffin moderator. The source is used for various activation experiments, where you can lower the materials to be activated into the two plastic tubes.
The AmBe neutron source is hidden in the paraffin block. Through the tubes you can immerse various materials for neutron activation analysis.
Here, I recorded the highest dose rate recorded so far, 320 µSv/hour. Again, this is probably not a very correct measure, since that area is flooded with neutrons as well. How neutron interact depends strongly on the target material.
320 µSv/h. Occupational limit is 20 mSv/year, public limit is 1 mSv/year, so let's quickly close the door again.
We have several dosimeters at the institute, so I tried to compare the elevated background with a calibrated device, the quite common and more pricey "Gamma scout" dosimeter:
Comparison of the SOEKS Defender against a Gamma Scout. In fact this was the best agreement I ever saw between the two devices.
They both measure the same background to approximately 0.7 µSv/hour, but the agreement varied a lot depending where in the room I was. Mostly, I noticed a considerable underestimation of the dose reported by the SOEKS device, sometimes up to a factor of 2. Probably this is just the precision you can get, it's good enough for my (non-work related) purposes. If you want high-precision monitoring, you need professional equipment which is well calibrated, and that is certainly a different price tag.
I also have a little Japanese silver medallion. I activated it by leaving it in on top of the AmBe paraffin block. Neutrons generate Ag-110 and Ag-108 isotopes with T_1/2 of 26 sec and 2.4 min, respectively. I could follow the cooling down of the medal with the dosimeter:
Japanese silver medallion activated by neutrons. After 15-30 minutes it cools down to normal background levels.
Various sources for student exercises.
Anyway, I still hope to find time to realize my Chernobyl visit, will certainly bring this handy device with me. :)
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P.s.: Not really related, I recently came across a very old video of how I in my young ages zapped a CCD detector using a medical linear accelerator. The chip suffering in the video is an engineering grade CCD47-20 by EEV (E2V / Marconi), which was intended to fly on a satellite mission. I later also irradiated one with protons. (Sorry, video is a polyglot mix of German and Danish.)
SHIELD-HIT12A is a Monte Carlo particle transport code capable of transporting heavy ions through arbitrary media. The -A fork was made in 2010 from SHIELD-HIT08, and since then we have added plenty of new features, solved many bugs, increased calculation speed and optimized the nuclear models to new data on carbon-12 fragmentation.
A free demo version where the random seed and statistics are fixed to 10.000 particles can be downloaded from the project development page. There are builds for Linux and Windows systems (32- and 64 bit). It is a beta-release, but we would like to bring this demo version to a broader community, and thereby hopefully also fix some more bugs before we release the full version.
The new features in SHIELD-HIT12A are:
New simplified material and beam parameter parser in free format and extensible without breaking downward compability.
New beam model: divergence and focus distance can now be specified (thanks to Uli Weber from Marburg).
Arbitrary starting beam directions now possible.
New routine for Vavilov straggling, 5-6 times faster than the original one by Rotondi and Montagna which was used in Geant3.21. In total, this alone means a speed improvement of roughly 30-40%.
Ripple filter has two modes of operation, Monte Carlo type or Modulus type.
Scoring by zones using detect.dat (complementary to Cartesian mesh and cylindrical scoring)
Alanine response model included, so SHIELD-HIT12A can directly calculate the dose equivalent response in alanine.
Flat circular and square beams can be defined
Neutron data for natural Argon was added (needed for detailed simulations of air)
Another ton of bug fixes.
Of course SHIELD-HIT12A includes the features from SHIELD-HIT10A (which was never released):
Totally new (parallelizable) scoring system:
Arbitrary Mesh and Cylindrical scoring
Lots of detectors such as energy, fluence, dose-averaged LET, track-averaged LET, average velocity (beta), dose to medium (where medium can be changed if you want to calculate stopping power ratios) etc....
finally SHIELD-HIT10A is parallelizable
New random number generator, which gives a massive performance boost
New adjusted inelastic cross sections for carbon ions based on recent data
Fine tuning of the fermi-breakup parameters
SHIELD-HIT10A can be configured without accessing the source code anymore, so no programming knowledge required to use SHIELD-HIT10A.
SHIELD-HIT10A is installable
Runs on linux again, even when compiling with code optimizations, ok with GNU gfortran, Intel and Portland compilers.
Many bug fixes
Enjoy! And please drop me a line when you find bugs in the software and errors in the manual, they are there, but we hid them well. :o)
This post is not related to computing, but more to medical physics. Primary standards dosimetry laboratories (PSDL) are important for medical physicists, since they define fundamental quantities such as dose. If you buy some dosimeter, say, an ionization chamber, it is most likely calibrated at a PSDL (for ample amounts of money) or a secondary standards dosimetry laboratory (SSDL) which is linked towards a PSDL. Not all countries have a PSDL or SSDL, and some countries (like Slovakia in this case) have both PSDL and a SSDL facilities. To my knowledge, Denmark quite recently got the SSDL status at the National Institute for Radioprotection.
During summer vacation 2011, after finishing the run at CERN, I had a rather messy tour across Europe and also went to Bratislava to visit some friends. Here I got the chance to get a tour of the Slovakian PSDL at the Metrological (not to mistaken with the Meteological) Institute. It is my second vist at a PSDL - a few years ago, I visited the PSDL at the National Physical Laboratory in the UK, but I only got crappy mobile phone pictures.
The Metrological Institute of Slovakia, Bratislava.
The director of the institute, Jozef Dobrovodsky gave me a tour of the facility. They have a close cooperation with the NPL - most physicists working with particle therapy may have heard of proton dosimetry expert Hugo Palmans who works at NPL near London, but (quite conveniently) actually lives in Bratislava.
Jozef and Hugo looking at Roos plane parallel ionization chambers from PTW, well suited for measuring depth-dose curves of pencil shaped ion beams.
Outline of the facility.
The facility has a Betatron, a Cobalt-60 unit, a 320 kV X-ray unit, a Caesium-137 irradiator and a neutron vault with various neutron sources.
Mock-up models of Cs-137 sources (these are NOT radioactive).
Probably the most important room is where the Co-60 irradiator is kept. Co-60 has a long history serving as reference radiation for a wide range of dosimetric tasks. Beam quality is usualy expressed relative to Co-60 standard. However, Co-60 irradiators are getting rare. Radiation treatment with Co-60 is rather something seen in developing countries, at most hospitals they were replaced with megavolt linear accelertors, also for safety issues. (Messing with radioactive sources is always a bad thing and should be avoided). As a researcher, it gets increasingly difficult to get access to a proper reference radiation.
The yellow box holds the Co-60 source, behind the tank an additional collimator is visible which can be mounted in front of the Co-60 unit.
Co-60 irradiation room. The tank holds a Markus ionization chamber, and the dose-rate can be reduced by increasing the distance to the Co-60 irradiation unit.
Next we took a look at the X-ray irradiation room. X-rays have lower energies than Co-60 and are made electrically and not from a radioactive source.
Two X-ray sources are seen here, one in the background with wheels of various copper filers which can be positioned in the beam. Copper filters can remove characteristic lines of the X-ray spectrum, thereby flattening it. In front an X-ray diagnostic device is visible.
How to make 90 Volts. :)
Cs-137 provide a photon field at about half the energy of the MeV Co-60 photons.
Cs-137 irradiation room.
Cs-137 irradiator seen from the front. Aperture can slide to the right, exposing the room to the source.
A real gem was their Betatron: it's a Czech construction, which can deliver both electron and photon beams. The betatron is an old design originally invented by the Norwegian Widerøe, who also invented the idea of drift tubes, widely used at almost any accelerator today. Betatrons (especially functioning betatrons) are a very rare sight today, most were replaced with LINACs long time ago. I once saw a betatron at the physics department of Freiburg in Germany, but it was not operational anymore. This one however is still functioning! (Look how clean and tidy it is... I am used to messy laboratories.)
Second time I ever see a betatron. Yay! :-)
You can extract either photons or electrons on either side. This is the photon exit (I think).
They even had a spare betatron tube, heavily tarnished by radiation damage to the glass.
Control console for the betatron. Nice and sleek.
Power supply and controls for the betatron. Many components are still genuine Czech, manufactured by TESLA.
Finally we visited the neutron vault. Here they had three neutron irradiators: two different accelerator based sources and a range of radioactive neutron emitters. The neutron sources were kept in a cave in the floor shielded with lots of plastic material for neutron moderation/absorption. The sources they have are quite common. Some intense alpha source (Plutonium or Americium) mixed with some light material (Beryllium). A Californium source was also there which fissions spontaneously.
Neutron vault. In the floor several neutron sources are kept, and can be raised out of the cave by the visible holder. I was a bit hesitant, when the scientist suddenly pulled a string, and the holder surfaced out of the neutron cave, as shown on this picture. “Is it empty?!” “Sure it's empty.”
This accelerator was very cute: protons accelerated towards a tritium target produces a neutron beam. The design of the high voltage terminal looks very much like the design found in the terminal of our Van de Graaf KN machine in Aarhus.
The ion source can be seen in the middle.
Beam is directed against a tritium metal hydride target, which is rotated to redistribute the dissipated power over a larger area. This produces a neutron beam, exiting to the lower left.
I always found acceletor technology very interesting, especially old designs where you easily can recognize what is going on (or not). If it is eastern-european design, it's just even more interesting, since they tend to look rather different and often show signs of various improvisations.
This is some Russian accelerator based neutron source. However, it was not really used if I remember correctly, and unfortunately I didn't pick up all the details about it.
I was once told that its very characteristic for Russian accelerator systems, that the vacuum tubes are fixed with 4 screws only.
This concludes our little tour at the irradiation facilities of the primary standard lab in Bratislava. Thanks to Hugo Palmans and Jozef Dobrovodsky for the tour!
An antiproton and a proton dosimetry researcher meet. No annihilation, but some sort of a bound state, clearly sharing common goals and interests.
