Marvin
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X-ray and γ Spectroscopy with PIN Photodiodes
X-ray spectroscopy with off the shelf PIN diodes.
http://freshlab.org/detektor/?lang=eng
There is complimentary information in the polish section. I did find more details in two documents elsewhere on the web, not a complete schematic but
enough to reconstruct the circuit. They used a discrete MCA but if the preamp/shaper can be made to work I think we can put something together with
an ADC.
http://fatcat.ftj.agh.edu.pl/bozon/dokumenty/referaty/ref_XL...
http://www-zeuthen.desy.de/students/2007/doc/SzymonKulis_rep...
I started work on this, calculating depletion thicknesses on diodes, ordering op amps but fizzled out. I'll attack it again soon.
<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: subject for
split topic]
[Edited on 20.1.14 by bfesser]
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bfesser
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I've split this from <strong><a href="viewthread.php?tid=25882">Interests in Radioactivity & Nuclear History</a></strong>,
as I think it's a subject worthy of it's own dedicated topic.
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IrC
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After trying a dozen different circuit approaches I am not very impressed with the BPW34 diode. Not real sensitive and the far better PS100-7-CER-PIN
is too expensive and too hard to find. Right now I am searching patents for phosphors to provide the light pulses, focusing in on materials which
quench extremely fast. Otherwise the persistence would be akin to a GM tube saturating in a strong flux. Found a few ideas for ZnS with activators
such as Sm. I am thinking on this line as a way to use the cheaper photodiode but as a photodiode instead of the actual radiation detector. Just
trying to move away from the photomultiplier route looking for a low voltage low current draw design. Even dug out my kiln for a few trials of making
my own phosphors. However from reading the patents the flux is critical and I get the drift that halide fluxes are not all that desirable. Since I
suck at chemistry, does anyone have any good ideas. One patent mentions Manganous Chloride but then goes off into listing problems using halides for
fluxes. Have not had the time to follow the patent holder through time to see if he has any later numbers with better ideas through trial and error.
Old 1941 patents for screens for radar where the sweep could be very fast without the trace glowing too long. I got interested in that phosphor as he
mentions its large light output when exposed to Xrays.
Will post it here when I have time to go through the folder and find it. Skimmed through a hundred and forgot to hold it out before dumping into the
folder of several hundred. When I reach a DVD in downloaded file size I burn them. Lost a couple weeks searching when a drive suddenly crashed once so
now I burn 3 copies of each full DVD's worth of downloading before I return to searching. What are some good ideas for flux? I typically have used
Strontium Nitrate but this was for my long persistence glow powder experiments, opposite what I want now. I am as yet unsure if using phosphors would
be a good way to gain amplitude as well as pulses per second information. Seems the diode alone would be faster not to mention phosphors may respond
very differently in terms of amplitude VS spectrum of the radiation.
I like to search patents for ideas. Less use of time if I study what worked or did not work, than using the Edison approach. On the idea of Xray
Spectroscopy an interesting patent along with the patents it references:
8357894 Microcalorimetry for X-ray spectroscopy
references:
20100148064 X-RAY DETECTOR FOR ELECTRON MICROSCOPE June, 2010 Harrach et al.
7232487 Method for making an epitaxial germanium temperature sensor June, 2007 Silver et al.
20060198494 Three-dimensional structure analyzing system September, 2006 Tanaka et al. 378/45
6594337 X-ray diagnostic system July, 2003 Silver et al.
6479818 Application of x-ray optics to energy dispersive spectroscopy November, 2002 McCarthy et al.
6310350 Multiplexed microcalorimeter array October, 2001 Silver et al.
6094471 X-ray diagnostic system July, 2000 Silver et al.
5880467 Microcalorimeter x-ray detectors with x-ray lens March, 1999 Martinis et al.
5777336 Broadband high resolution X-ray spectral analyzer July, 1998 Silver et al.
5389792 Electron microprobe utilizing thermal detector arrays
[Edited on 1-20-2014 by IrC]
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"Science is the belief in the ignorance of the experts" Richard Feynman
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WGTR
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That's a good find. I'm going to have to file this topic away for future reference. I'm a little busy with other things right now.
Some time ago I was thinking about what it would take to build a DIY electron microscope. It seemed pretty doable,
except for the detector. Something like this might actually fit the bill.
Regardless of what is used, the detector will probably have to be cooled down.
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IrC
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Cannot put too many files in one post thus this post.
2843750 Chi-ray spectrometer
2704331 Adjustable mount for chi-ray diffraction crystal
2635192 Fluorescent spectral analysis
2645720 Chi-ray diffraction device
Attachment: US2843750A.pdf (263kB)
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I have searched for a long while but still cannot find the definition for Chi Ray. Other than it's mention in patents around the 1920's to 40's. Many
hundreds of patents. Read many of them and every time they assume you already know in the wording. My guess is Xray, yet in the same era they often
use Xray. So my next guess is Gamma. Am I hot, cold, clueless?
[Edited on 1-20-2014 by IrC]
"Science is the belief in the ignorance of the experts" Richard Feynman
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Hitachi R1200
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Chi may refer to the Chi axis in 4 circle X-ray diffractometers, where chi is indicated by the Greek symbol that looks like a funny X.
http://www.ems.psu.edu/~ryba/coursework/530/four-circle.html
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IrC
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Sounds reasonable except in most of the patents with titles such as 'Chi-Ray tube', the tube is exactly like an Xray tube, the tube being the sole
subject of the patent (in many). My best guess was in the early days there was no global consensus as to name since in the same span of years patents
also exist showing similar tubes but titled 'X-Ray tube'. Then again it seems over the years the name 'Xmen' remained the same so who knows. I looked
at hundreds of google hits and if they were technical they were invariably patents. Seemed odd that in the global internet no one has ever covered the
subject or given an explanation. Lost to time?
Look at the 1900-1905 date:
----------------------------------
gamma radiation
gamma ray
noun Physics.
1.
a photon of penetrating electromagnetic radiation (gamma radiation) emitted from an atomic nucleus.
2.
a photon emitted by an electron as a result of internal conversion.
3.
electromagnetic radiation with wavelengths shorter than approximately one tenth of a nanometer.
Origin:
1900–05
Collins World English Dictionary
gamma radiation
—n
1. electromagnetic radiation emitted by atomic nuclei; the wavelength is generally in the range 1 × 10--10 to 2 × 10--13 metres
2. electromagnetic radiation of very short wavelength emitted by any source, esp the portion of the electromagnetic spectrum with a wavelength less
than about 1 × 10--11 metres
-------------------------------------------------
From this it seems as far back as 1900 Gamma means Gamma.
Searching google with "chi-ray radiation definition", first hit Gamma, 2nd cosmic, 3rd Gamma on wiki, then patents. What does google know they are not
saying since they start out with Gamma when searching for Chi?
Patent US2998524 - Monochromatic chi-ray source - ... 'MONOCHROMATIC X-RAY SOURCE'
Patent US1953813 - Chi-ray tube..... 'One of the objects of my invention is to reduce undesired X-ray radiation from 5 the back of the target and thus
to promote sharpness of definition in radiographs'
From this I conclude for some reason 110 years ago X and Chi were used interchangeably, yet note the odd use of both in the same patent US1953813
above. Confusing.
I suppose not important and possibly irritatingly off topic to Marvin but some of the patents I posted use the name and I would really like to know if
anyone still lives who does know.
I found this when I changed my search by adding 'definition' (I first just searched 'Chi-Ray tube' or 'Chi-Ray'):
"Terahertz radiation (or submillimeter waves) are nestled right in ... pulled his info directly from the wiki http://en.wikipedia.org/wiki/Terahertz ... As for Chi, logically it should be X-ray, since that's the next major specter above UV." at:
http://brentweeks.ning.com/forum/topics/questions-about-chi-...
While this last link is about fiction, it seems no one else online discussed the subject.
PHOTODIODE AMPLIFIER
European Patent Application EP1790073
Attachment: EP1790073A1.pdf (636kB)
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[Edited on 1-20-2014 by IrC]
"Science is the belief in the ignorance of the experts" Richard Feynman
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neptunium
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have you looked at the phosphor used in CRT ? there must be millions of them in land fill after the invasion of flat screen TV..
they have a very fast response time and are easy enough to collect. an old neon tube with rare earth phosphor could work as well...
But these substances are not transparent and can only be used for particle detection (alpha or beta) gamma and X need more volume to be absorbed and
give off their energy hence a transparent scintillator... have you looked at BC412 ? the plastic scintillator? they go for much cheaper than crystals
on ebay but are not as dense and you would need quite a few for a spectrometer..
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bfesser
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I've had this in my eBay watch list for months:
<a href="http://www.ebay.com/itm/261194548206" target="_blank">2" Diameter Round Scintillator Plastic for Scintillation Detector 2" X
1-1/2"</a> <img src="../scipics/_ext.png" />
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IrC
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Quote: Originally posted by neptunium  | have you looked at the phosphor used in CRT ? there must be millions of them in land fill after the invasion of flat screen TV..
they have a very fast response time and are easy enough to collect. an old neon tube with rare earth phosphor could work as well...
But these substances are not transparent and can only be used for particle detection (alpha or beta) gamma and X need more volume to be absorbed and
give off their energy hence a transparent scintillator... have you looked at BC412 ? the plastic scintillator? they go for much cheaper than crystals
on ebay but are not as dense and you would need quite a few for a spectrometer.. |
Yes I have used it but only with PMT's. Was trying to get away from that and a large area photodiode is expensive as well as hard to locate. So much
so I entertained the idea of finding a way to use the CCD for a Sony DSC-F707 but I was unsure of how one would achieve that even though I had a few
of those on hand. For fast response BC422 (EJ232) makes more sense. I have never been that impressed with BC412 even with a 9727B 2" PMT. I always end
up going back to NaI/Tl using Optical coupling grease. Spendy. Is that a word? I have melted 3 lbs of borated parafin, poured in blender folding in an
ounce of silver dust trying to reach a very uniform mixture then pouring into a mold, inserting a glass cigar tube just larger than a 6306 GM tube.
Tried to wait until the blender was dragging badly as I wanted to keep the silver dust from settling as it cooled. Gently heat glass tube, remove,
insert GM tube. Mount in large plastic project box with 4 pin mile jack, coiled cord, jack on other end. Mounted similar jack on a CDV700 and modified
it's probe cord so I can quickly plug in one or the other probe (pic below). This was an attempt at neutron detection. Did a similar trial with molten
Bicron and silver dust. Blender doom. In any case I just do not think these plastics are right for using a photodiode circuit. A large area photodiode
as the detector itself seems the only sensible yet expensive approach. Do not want to turn the thread away from Marvin's purpose but didn't see how to
answer your question without going somewhat off topic.
My reason for posting in this thread is to see what people who know more about the subject think of using the BPW34 (because its cheap and I have a
few dozen) to look at a target which itself does the scintillating. Mainly because the diode itself is just too small and insensitive in my opinion.
My goal is cheap, low power detector on one hand, as well as my interest in spectrometry to actually determine if possible what type and energy the
radiation is. All in a handheld portable device. Oddly enough I see similarities to designing metal detectors. Modern models running Pics or similar
processors use look up tables of amplitude and phase differences in signals (the shape of the pulse) to determine is it a quarter, beer can, foil tab,
Germany's missing gold, what type metal, and so on. In effect what is the element, how many uCi (or other units). From this one could determine is it
natural, fallout, how strong is the flux and so on.
While these links are more for PMT's I include them for the information on Bicron and typical use since you mentioned BC412.
http://www.eljentechnology.com/index.php/products/plastic-sc...
http://hardhack.org.au/book/export/html/83
| Quote: Originally posted by bfesser | I've had this in my eBay watch list for months:
<a href="http://www.ebay.com/itm/261194548206" target="_blank">2" Diameter Round Scintillator Plastic for Scintillation Detector 2" X
1-1/2"</a> <img src="../scipics/_ext.png" /> |
One thing I tried with my Bicron was a polish kit from Auto Zone for car headlights. Works very well. Also low cost optical coupling grease is on
ebay.
Anyway the talk of Bicron moves us away from Marvin's purpose I think as I see no other reasonable way to use this plastic without a PMT. I could be
wrong. Which is why I included a few documents on the subject. Can a photodiode replace a PMT? Say with a lens to focus a larger area from the
scintillator onto the smaller diode or would the loss render the idea useless? What about a scintillator plate of proper size coupled with optical
grease to the BPW34?
Getting back to my question about using a CCD. I saw this on page 33 "pixelized photodiodes operated in Geiger mode" of the PDF 'Lecture4.pdf'. 10 mb
so cannot upload. This is what made me wonder if a CCD for my Sony can be made to operate as a large area detector, also if alone as the detector, or
looking at a screen which brings me back to my phosphor questions. Hoping Marvin will study the PDF linked below on page 33 to see if my thought about
a CCD is possible.
Borated paraffin Ag dust GM tube probe:
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Link from google to lecture4.pdf:
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&a...
"Science is the belief in the ignorance of the experts" Richard Feynman
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IrC
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Don't want to post too many files in post above for fear of messing it up. Off topic but added to be complete in above description. IIRC the original
meter croaked so I stole one from a CDV715. Or I put all the guts in a 715 I just don't remember it's been nearly 15 years since I built this. By
changing probe it is a Geiger counter or Neutron detector (big black box in post above). As you can see I added a mike jack to allow probe changing.
Low to no leakage of the high voltage using the mike plug and jacks, all in all it worked out very well.
Sorry about the off topic posting Marvin.
Forgot to say the entire circuit is my own, auto zero, allowing me to mount a 1/4" headphone jack for phones in the location the zero control once
was. The only thing CDV related was the box, meter, rotary switch, and Geiger probe. Little holes near serial number are for fairly loud piezo mounted
underneath so clicks are decent volume when headphones are not desired. Installed it to hear low number of clicks when meter would not give much
information. My Be half spheres from some military gyro application are loaded with Am241 bits from old smoke detectors yet do not produce all that
many neutrons.
[Edited on 1-21-2014 by IrC]
"Science is the belief in the ignorance of the experts" Richard Feynman
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neptunium
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and you wont get enough neutron with smoke detector's Am241...
generally speaking a neutron is produced from Be every few million impact of alpha particles. those smoke detector are about 10 uCi or 37 000 bq
(decay per second)
you`d need at the minimum 100 of them or about 1mCi (100 times more) but 1000 would let you perform neutron activations.
when a neutron is made it can shoot in any direction with an energy too great to be capture by a nucleus and is going to bounce arround and likely
escape the experiment.
it has to be slowed down to a thermal energy range by hydrogenated substances 9like water or wax) . to be detected by a slow neutron detector )unless
of course you have a fast neutron detector)
I had the idea of a CCD array to detecttiny flashes of light from a scintillator too! but the photodiode i am affraid might not be sensitive enough i
am affraid, and i dont know if it could pick up the correct wavelengh,
How will you turn the signal from a CCD to a pulse with height matching the intensity of light from the crystal?
i have this CCD camera and software originally designed for astrophotography that can be exposed for extanded period of time i suppose one could set
it up focused on a scintillation platte (like the Xray screen ) and could do a gammagraphy of an area and pick up hot spots ..
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Polverone
Now celebrating 21 years of madness
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Thread Moved
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