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Questions tagged [gamma-rays]

Electromagnetic radiation with high energies and a typcial wavelength of less than 10 picometers.

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Analysis on gamma-ray spectrum [on hold]

I am having trouble with the analysis portion of my experiment. My group has performed gamma-ray spectroscopy on several radio active sources. I am to identify these materials through our analysis. ...
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33 views

Half thickness of lead using a Ba-133m source, references?

I carried out an experiment to calculate the half thickness (half value layer) of lead. The experiment was done using what i believe to be a Ba-133m source on this software: https://radiation-lab....
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Why Li is not added as contact by ion implantation method in p type HPGe detector? [duplicate]

n+ contact of p type Ge is ~700µm thick compared to p+ contact of n type Ge only ~0.3µm. The process of adding the contact is different. n+ contact Li is added by diffusion process but p+ contact B is ...
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Calculating the shielding required to protect against radiation at lunar orbit

I am attempting to calculate the thickness needed to protect the crew inside a space module at the Lunar Orbit with Lithium Hydride from X and Gamma Rays. How would I calculate the thickness of Li-H ...
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Has there been any R&D(let alone progress) in the development of gamma voltaic cells?

I ask this because it is my understanding that gamma rays form ion tracks and oxygen radicals when gamma emitting material is immersed in an aqueous solution. Cesium-137 is a very strong gamma ray ...
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1answer
33 views

Gamma spectrometry: effect on one peak when adding another source

Suppose I have a sample containing only 137Cs. Now assume it shows 1000 cps counts for 137Cs, 662keV energy. Now I added 60Co (1173, 1332 keV) source in the same sample. Compton scattering ...
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23 views

Questions regarding germanium detector

Why n+ contact in n type Ge is not several hundred microns? . Why we require both additional p or n type contact? in p type Ge, why we require additional p type junction also? crystal itself should ...
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Why n+ contact of p type Ge is 700um thick compared to p+ contact of n type Ge only 0.3um?

Whether the reason is as follows? Predominantly HPGe is p type. So compensation of large p type impurity requires more n+ contact. (700um) But n type Ge is made by doping of excess addition of n type ...
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36 views

Dark Matter gamma-ray flux from hadronic annihilation channels?

For a project I am currently reading into indirect detection of Dark Matter via gamma-rays from DM subhalo's. I understand that there is a possibility of DM annihilating with each other in these ...
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1answer
27 views

Higher frequency waves

Can we artificially create extremely high frequency waves in the ( order of 10^60 )? how hard is it to create high frequency waves, and what limits are potential in doing so...
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1answer
82 views

Nuclear reaction – What is the asterisk an indication of?

I've been observing the two-step decay of iodine-131 and can't quite determine what the asterisk above Xenon-131 indicates. I'm currently unsure as to what precisely the superscript asterisk on Xenon ...
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3answers
75 views

Why would gamma spectroscopy be a tool for nuclei?

I am very much familiar with Atomic spectroscopy, not much with nuclear spectroscopy. In atoms (electronic cloud), we have electromagnetic interaction that plays the leading role, whose exchange ...
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2answers
44 views

Absolute measure of activity

I am generally quite stuck and not sure what the absolute measure of activity is, and relating to my data is more confusing. So I am trying to calculate the absolute measure of activity of a caesium ...
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1answer
63 views

List of Gamma Ray Spectrum Values

I am trying to identify the peak which is occurring in my caesium 137 spectroscopy graph, and trying to find a creditable source with a list of most if not all gamma decay spectrum values for all ...
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1answer
44 views

In HPGe detector how electron-hole pair remembers energy information of incident gamma?

In the HPGe detector, any gamma energy (> e-h pair production E) shall excite the electron of the valence band and send it to the conduction band. Due to reverse bias, the conduction band e shall be ...
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1answer
253 views

How in Cesium 137 spectroscopy Barium X-rays being detected?

Iv been looking at gamma ray spectroscopy of late for a project that I am currently researching and going to be doing in the lab, but what I cannot seem to figure is how the barium x-rays are being ...
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1answer
71 views

Gamma ray spectroscopy lab experiment : Cobolt 60 Data

I am currently carrying out an a gamma ray spectroscopy experiment. At this moment in time I am trying to decipher what parts of the gamma spectrum are what, i.e Compton edge, backscatter, photo peaks ...
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1answer
43 views

Probability of Photoelectric Interactions

I have am currently reading Radiation Detection and Measurement, by Gleen F.Knoll, and in chapter 2 page 49, he talks about the probability of the photoelectric interaction as: $$\tau \approx C \frac{...
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1answer
43 views

Gamma Ray Spectroscopy-What Happens With Inside the Scintillation Crystal

I am going to carrying out an investigation in the lab on gamma ray spectroscopy and to help me understand the graphs that will be displayed to me, I am researching on the types of interactions that ...
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1answer
169 views

What would happen if gamma-ray burst from a supernova burst hit the sun? [closed]

What would happen if gamma-ray burst from a supernova burst hit the sun? Would the sun explode? Would the sun expand. Have a longer lifetime? Shorter Lifetime? Because people are nit-picky about stuff ...
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33 views

Theoretical models of short Gamma Ray Bursts

I have recently been interested in the currently known theory behind short gamma ray burst (sGRB) models. I can't seem to find any available source which shows the theory behind the relativistic shock ...
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3answers
246 views

Wavelength and penetration by EM radiation

I'd like you to clarify the relationship which relates penetration power by EM radiation with its wavelength (or inverse of frequency). Suppose we conduct an experiment, irradiating a body with ...
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1answer
170 views

Electron-positron annihilation/creation

I understand that gamma-rays can produce positron-electron pairs and positrons and electrons can annihilate to two gamma-rays. My question is: If a gamma-ray photon creates a positron-electron pair, ...
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1answer
99 views

How can gamma rays affect a human body if they can move through atoms without colliding with them?

I found this answer on this SE about why mirrors don't reflect gamma rays, and the answer says that it is because gamma rays are so, so small that they "see mostly empty space between the atoms of the ...
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3answers
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Why does a mirror reflect visible light but not gamma rays?

Visible light (~500 THz) as well as gamma rays (~100 EHz) are electromagnetic radiation but we can reflect visible light using a glass mirror but not gamma rays. Why is that?
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1answer
88 views

Where do ultrahigh-energy particles come from? [duplicate]

The most energetic particles that strike us from space, which include neutrinos as well as gamma-ray photons and various other bits of subatomic shrapnel, i.e the cosmic rays are sometimes so ...
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2answers
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Is it possible to see traveling light beams?

As we all know the speed of light is the thing that allows us to see Now let's imagine a beam of gamma rays from a Black hole just a few light years away passing through the solar system somehow was ...
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0answers
38 views

How do you calibrate a proton-recoil scintillation fast neutron detector?

I have a proton recoil scintillator, but gamma sources like Cs-137, Co-60 don't seem to have linear calibration for the device. Are there other ways of calibrating this device? I'm trying to detect ...
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1answer
487 views

How many inches of lead would it take to stop the gamma rays equal to 8 inches of concrete ?

I have searched high and mighty on google and it is hard to find a comparison chart of different materials and their effectiveness to stop radiation from fallout. I am assuming the fallout source is ...
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56 views

Which radionuclides do not emit gamma rays?

Radionuclides that do not emit gamma rays are useful for radioluminescent materials and nuclear batteries because they don't require gamma ray shielding. Most radionuclides seem to emit gamma rays in ...
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1answer
235 views

About the existence of anti-photon [duplicate]

How can be explained the phenomenon of two related Gamma rays ending their courses by becoming an electron and a positron without the involvement of a photon and an anti-photon ? This question must be ...
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2answers
84 views

Why electron positron pair move oppositely inspite of attraction?

In pair production the two antiparticles always move in opposite direction I wonder why is that so though I know it is to conserve energy but the basic principle unlike charged particle attract should ...
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1answer
62 views

Frequency of neutron versus gamma emission by a radioactive source

Given gamma and neutron emission spectra for a radioactive source, say PuBe-239 for example, is there a way to calculate what fraction of total particles emitted are neutrons or gammas? If not, what's ...
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2answers
55 views

Gamma ray guns?

If you had a super powerful gamma-ray creating gun what would it be like? Would it be similar to on sci-fi shows where they have laser guns that can pierce a hole through an enemy more effective ...
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1answer
422 views

Why does doping a Sodium Iodide scintillator with Thallium result in a higher ratio of Compton interactions to total interactions?

We are looking at designing a Compton camera for 662KeV photons and have been told that "the fraction of Compton interactions to total interactions in the photopeak is usually higher than fraction in ...
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2answers
936 views

What makes the thorium-229 nuclear transition special?

Thorium-229 has a famous isomer with an excitation energy of only about 7.8 eV. As I gather from the wikipedia page, this transition was discovered essentially by accident from gamma ray spectroscopy....
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2answers
558 views

How is gamma ray blocked in the atmosphere in cosmic rays? [duplicate]

I would like to know how gamma rays from cosmic rays are blocked by the earth's atmosphere. I know that the sun's gamma radiation don't usually reach the earth so I wouldn't be worrying much about it. ...
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1answer
34 views

What can be the effects over the path itself of a gamma-ray burst traveling between two intermediate points of space-time?

We assume that a gamma-ray burst travels from a source $S$ to a target $T$, and we consider how our gamma ray interacts with our path, when our ray travels between two intermediate points (in space-...
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2answers
1k views

Why do we use radio waves for communication when gamma rays are more powerful? [duplicate]

NASA and other space programs primarily use radio waves to transfer information from spacecraft back to earth. Why don't they use gamma rays, which are more powerful? Since radio waves have less ...
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2answers
488 views

Why Compton scattering probability for gamma ray increases and reaches a maxima and finally decreases with energy? Non mathematical answer please

It is seen from mass attenuation vs energy plot thar compton scattering cross section goes through a maximum. It is low at low energy and high at high energy. Why? I want a non mathematical answer. ...
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81 views

Probability of photoelectric effect for gamma rays [duplicate]

Why is the probability of the photoelectric effect occurring higher for low energy gamma rays? I'd like a physical answer not just equations.
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2answers
160 views

Book says that gamma rays don't ionise atoms as they pass through matter?

I am reading the book The Greatest Story Ever Told ... So Far by Lawrence Krauss, and I came across this in chapter 9: In 1930 Bothe and his assistant Herbert Becker observed something completely ...
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1answer
63 views

Can a gamma-ray burst affect the same place of the space twice times?

I know that the space-time has curvature. Also I have basic knowledge about the gamma-ray bursts. I would like to know if a same pulse of GRB can affect the same place of the space twice times. Is ...
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2answers
133 views

How to analyse gamma ray spectra?

I have recently done an experiment using gamma radiation and am now at a loss as to how to analyse the data I acquired. I have a background spectrum and a spectrum from a radioactive sample and need ...
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2answers
68 views

how close to radioactive material to be detected

I am not expert on this but we have a project to detect radioactive material, we have found an off-the-shelf devise where its sensitivity for gamma rays starts from 20 KeV. My question is if you have ...
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94 views

Method of determining the 3 peaks of a Cd-109 Gamma Ray Spectrum

I took a full spectrum of Cd-109 and the result was a peak around 5 keV, a peak around 22 keV, and a peak around 87.85 keV. I know that there are actually supposed to be two peaks around 22 keV, but ...
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1answer
23 views

Are radiation interactions pressure, temperature dependent?

I read somewhere that gamma radiation interact with matter mostly via Compton scattering. I guess there are other type of interactions as well and probably a constant ratio between them. Does this ...
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2answers
69 views

Two photons (experiment) and light speed. Why? [closed]

I found a part of a popular-science film on YouTube: https://www.youtube.com/watch?v=-vrJxRCf4-E (Please see around 24:10 on this video) I have a small question. An example with two photons is ...
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4answers
8k views

Why did the gamma ray burst from GW170817 lag two seconds behind the gravitational wave?

The ABC, reporting on the announcement of gravitational wave GW170817, explained that for the first time we could identify the precise source of a gravitational wave because we also observed the event ...
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1answer
56 views

What is the actual significance of increasing efficiency of a detector?

Say, I have a gamma detector with a 80% detection efficiency. And I buy a new one, with 85% efficiency, or even 90%. How exactly does it benefit me to be having 10% greater efficiency, other than to ...