does a gamma ray scillinator pick up x-rays? - Page 1
Forum section: electronics / projects

author: CopperCone
author_rank: Super Contributor
timestamp: September 17, 2017, 11:45:38 pm
content: I have one meant for gamma radiation. Does it also pick up xray radiation?

author: Old Don
author_rank: Regular Contributor
timestamp: September 18, 2017, 01:05:12 am
content: I always used the following not quite exact rule of thumb --> Gamma Ray = a natural occurring non-particle radiation and Xray = man-made gamma rays. Alpha = hydrogen atom stripped of its electrons. Beta = electrons. Proton or neutron radiation are exactly as their names suggest. So if the device can read natural gamma rays of a certain energy level then it can also read man-made X-rays in the same energy band. Once created they are the same.OBTW, neutrinos are also flying around, but to detect them you'd need a detector deep into a mine shaft or a couple of 100 miles of lead to block since they pass right through most matter (including you and I).

author: borjam
author_rank: Unknown
timestamp: September 18, 2017, 06:04:37 am
content: Quote from: Old Don on September 18, 2017, 01:05:12 amTo be precise...Gamma rays: electromagnetic radiation originated in nuclear reactionsX Rays: Electromagnetic radiation produced by ionization reactions not involving the nucleusAlpha are actually He nucleus (2 protons + 2 neutrons)But yes, a photon is a photon regardless of what phemonenon produced it so there is some overlap in the energy levels of gamma and X rays.

author: Old Don
author_rank: Regular Contributor
timestamp: September 18, 2017, 01:08:17 pm
content: Quote from: borjam on September 18, 2017, 06:04:37 amOops, correct He not H nucleus. I knew that, but old brain cells .......

author: borjam
author_rank: Unknown
timestamp: September 18, 2017, 01:11:59 pm
content: Quote from: Old Don on September 18, 2017, 01:08:17 pmHehe (pardon the pun!)

author: Old Don
author_rank: Regular Contributor
timestamp: September 18, 2017, 02:52:04 pm
content: Ouch!

author: CopperCone
author_rank: Super Contributor
timestamp: September 18, 2017, 10:46:23 pm
content: I differentiate from xray and gamma be frequency and wavelength. I guess I should have asked what is the bandwidth of signals that can produce scintillation from a Sodium Iodide crystal doped with thallium.I'm pretty sure you can make gamma and x-ray lasers, eventually.

author: eliocor
author_rank: Unknown
timestamp: September 18, 2017, 11:34:50 pm
content: For some answers to your questions (and even more!) read carefully the first 53 pages of this wonderful document:http://sites.fas.harvard.edu/~phys191r/Bench_Notes/B1/NAI_catalog.pdfbut in few words: sensitivity to different photons energies depend on size of scintillator and (on the lower energies) on the material of the can containing your scintillator: if it has a berillium window you can go to few keV

author: IRFP460
author_rank: Contributor
timestamp: September 18, 2017, 11:42:36 pm
content: If it's some sorf of plastic scintillator look a the datasheet, if it's NaI, CsI, etc then yes, it does. Although most bigger NaI scintillators i've come across had a rather thick aluminium casing which will filter out your lower end.And to the X-Ray / gamma discussion:I was taught that gamma comes from the nucleus, and X-Rays are emitted by interactions with electrons, like Bremsstrahlung, Synchrotron radiation, electron positron annihilation etc.Now of course that definiton is not perfect, but the name gives a "feel for what is happening".

author: Old Don
author_rank: Regular Contributor
timestamp: September 19, 2017, 12:54:51 am
content: Quote from: IRFP460 on September 18, 2017, 11:42:36 pmAll true, but once free and out in the "world" and if both are at the same energy then they act exactly the same and detecting only depends upon the detector used.

author: TimFox
author_rank: Super Contributor
timestamp: September 19, 2017, 08:33:46 pm
content: The ranges of photon energy, and therefore frequency and wavelength, of common gamma and x-ray photons overlap each other greatly.For example, in high-energy radiography Co-60 gamma photons are approximately 1 MeV, DC x-ray tubes go up to about 450 keV, and linear-accelerator x-ray sources range from about 1 MeV to above 20 MeV.

author: CopperCone
author_rank: Super Contributor
timestamp: September 19, 2017, 09:09:11 pm
content: it would be refreshing if they had some kind of difference between them (though break physics?).. it would imply that frequency wavelength and speed of light equation is missing two other variables that are proportional and isolated from the other ones (so they could be treated as coefficients in the equation that we know), unless of course there is measurement error we don't know about (I believe this is a fairly well tested physics theory that we basically accept as cold hard law). some kind of photon parameters.

author: jmelson
author_rank: Super Contributor
timestamp: September 20, 2017, 03:29:27 am
content: Gamma rays and X rays are the same thing, just differentiated by energy (and sometimes the method of creation). Under 100 KeV is X ray, over 100 KeV is a Gamma ray. Now, as energy goes up, the gamma ray tends to sail right through the scintillator without interacting, so detection efficiency goes down. You need a bigger scintillator, or a denser one, to have high detection efficiency. On the other end, as energy goes down, the light produced when the low-energy Gamma or X ray is absorbed decreases, so whatever is sensing the light needs to be more sensitive.(Then, of course, there is Compton scattering of Gamma rays from scintillators, that opens up another whole dimension of complexity.)Also, the scintillator would need to be shielded from light in most cases, and the shield might absorb the X ray before it even reaches the scintillator.So, a scintillator intended for low-energy Gamma and X rays would need a very thin window/light shield, while one intended specifically for gammas might use a thicker shield to exclude the lowest energy rays.Jon

author: TimFox
author_rank: Super Contributor
timestamp: September 20, 2017, 07:32:35 pm
content: Again, the energy of the photon does not determine if it is a "gamma" or an "x-ray" photon.For example, before retiring, I often used electron-linear-accelerator x-ray sources at 6 and 9 MeV.Iodine-125, often used in radiotherapy, produces a gamma at 35 keV (through Te-125 as an intermediate state).

author: CopperCone
author_rank: Super Contributor
timestamp: September 21, 2017, 02:24:51 am
content: Well, If I understand correctly, this is a nomenclature issue, as you say that the name of the radiation implies that it was born of nuclear decay, but it is commonly shown on various EM spectrum charts (perhaps not correctly), that the classification of gamma pertains to a particular energy.I have also heard the term gamma used with various phenomena (wikipedia has a list "Gamma rays from sources other than radioactive decay")I don't know where the deviation began. Nor do I know if gamma created by atomic decay is different then gamma created by other things (though this is extremely unlikely, perhaps there are some fringe (not saying this in a bad way, just unpopular due to lack of academic interest, (all routes must be explored)) theories that basically state that not all photons are photons, but infact are something that falls into the photon category with various flavors like quarks, with some kind of spin number, color, etc).I personally feel that the universe would be rather boring if all photons were the same and only varied by energy.I think according to gauge theory, this would imply that there are at least four types of photons, if the ones emitted by nuclear decay are different.I suspect however that this is just a disagreement between electromagnetic and radiation researchers.Since you worked with the stuff, do you have a good understanding of the mechanism of the gamma creation vs other sources that could determine if its some how different? could be a noble prize lol

author: borjam
author_rank: Unknown
timestamp: September 21, 2017, 06:30:35 am
content: Quote from: CopperCone on September 21, 2017, 02:24:51 amProbably the reason for the different names is historical. I remember, some time ago, reading a textbook on Nuclear Physics. It described the disintegration reactions as a chain of byproducts whose names derived from the original element. So, for example, if it was Thorium the byproducts were called "Transthrorium" or something like that.Those names were used before the existance of isotopes was known and it was found out that those "Transthorium" were actually Radium, etc. I guess the same happens with Gamma and X rays.Nomenclatures can be curious sometimesAstrophysicists use to call "metals" elements with an atomic number higher than 2

author: CopperCone
author_rank: Super Contributor
timestamp: September 21, 2017, 07:22:16 am
content: In my opinion perhaps the deviation is good because it promotes further study to determine if it is warranted or not.Hard to find out about photon parameters though.