Gamma Definition and 714 Threads

  1. B

    Radio waves to gamma particle question

    Hi all, so iv'e been looking around and can't find an answer to a question i have. I have read articles on wikipedia and understand the "basics", but i still cannot fully visualize the concept. Question: Do all frequencies on the em spectrum emit the same particles? i know that visible "light"...
  2. T

    Approximating the gamma function near x=-3

    I've just started self studying James Nearing's "Mathematical Tools for Physicists" (available at http://www.physics.miami.edu/~nearing/mathmethods/mathematical_methods-three.pdf), and I'm having trouble with problem 1.16 about the gamma function, defined for positive x as \Gamma(x)=...
  3. M

    Gamma Spectroscopy for Estimating Radiological Risk in Rocks

    Am currently doing an undergraduate project work on 'estimation of radiological risk pose by U-238, th-232 and K-40 in rock samples' . The instrument I'll use are NaI(TI) crystal for scintilation were the gamma rays from the source(my rock samples) interact with the crystal through photoelectric...
  4. B

    Factorial Notation for Gamma Function Expression with Fractional Input?

    Hi members, gamma (n+1)=n! Now I have the following: gamma(2(n+3/2))=gamma(2n+1) What is factorial notation for this?? Thank you
  5. S

    Gamma Ray Ionization Path to Overcome Potential

    If a gamma ray is being fired and is in turn colliding with electrons and ionizing the electrons in the gamma ray path, where do the electrons tend to? In what direction is the current most likely to flow for a high powered gamma ray ionization?
  6. alyafey22

    MHB Prove Log Gamma Integral: $\sqrt{2 \pi}$

    Prove the following \int^1_0 \ln\left( \Gamma (x) \right) \, dx = \ln \left( \sqrt{2 \pi } \right)
  7. M

    Radioactive Source Emitting Only Alpha and Gamma Radiation

    Homework Statement "How could you show that a radioactive source was only emitting alpha and gamma radiation?"The attempt at a solution This really stumped me...obviously they have different penetration distances, and different strengths of ionisation, but I don't know how to show that only...
  8. L

    E+e- -> gamma f0 -> gamma pi0 pi0 cross section with VMD

    e+e- --> gamma f0 --> gamma pi0 pi0 cross section with VMD Homework Statement Find the cross-section of ##e^+e^- \to \gamma f_0(980) \to \gamma \pi^0 \pi^0## using the vector meson dominance model. Homework Equations Some Feynman's rules: The photon propagator is -i...
  9. C

    Show the gamma density function integrates to 1

    Homework Statement Show the gamma density function integrates to 1.Homework Equations Assume α > 0, λ > 0, t > 0 g(t) = \frac{λ^α}{\Gamma (α)} t^{α-1}e^{-λt} \Gamma (α)= \int_0^∞ t^{α-1} e^{-t} dt The Attempt at a Solution Show \int_0^∞ \frac{λ^α}{\Gamma (α)} t^{α-1}e^{-λt} dt = 1...
  10. M

    Is Cs-137 Effective for Calibrating Vintage Geiger Counters?

    So I have a bit of a story here. First of all, I work in my university's radiation safety department, where, among other things, I calibrate Geiger Counters. I also passed Modern Physics (Physics III), so I got some education on radioactive decay. I have an old Counter from 1962, a...
  11. M

    Why isn't there Cosmic Visible Background Radiation from gamma rays?

    If what used to be visible light when the universe was smaller and younger has been stretched due to the Doppler effect so that it is now microwaves and detectable as the Cosmic Microwave Background Radiation that can be found everywhere, why hasn't the gamma or x-rays of the same period not...
  12. B

    Trace of a product of gamma matrices

    Homework Statement A proof of equality between two traces of products of gamma matrices. Tr(\gamma^\mu (1_4-\gamma^5) A (1_4-\gamma^5) \gamma^\nu) = 2Tr(\gamma^\mu A (1_4-\gamma^5) \gamma^\nu) Where no special property of A is given, so we must assume it is just a random 4x4 matrix. 1_4...
  13. Mandelbroth

    Trouble with Calculating Gamma Function Integral Convergence on Wolfram Alpha?

    This is mostly calculus, but the question is computer based, I think. The antiderivative of the gamma function is, fairly trivially, ##\displaystyle \int_{0}^{+\infty}\frac{t^{z-1}}{e^{t}\ln{t}}-C##, where C is an arbitrary constant. Why does Wolfram Alpha have trouble calculating the...
  14. M

    What Do Peaks in Gamma Radiation Absorption Data Indicate?

    After performing this experiment, we will get different peaks on the computer screen, where on x-axis lies thickness of the absorber and on the y-axis the nb of channels. What do these represent exactly? Why do we have a high peak and a medium sized one? What are the significances of each...
  15. B

    The Purpose of Gamma Distribution

    I have to understand why someone would the Gamma Distribution, what does it tell it me when i use it or why would i use it in the first place?
  16. D

    Question regarding gamma function

    Homework Statement I have a quick question about the gamma function. According to my textbook it says: \int_{0}^{\infty }{{{x}^{n}}{{e}^{-ax}}dx}=\frac{\Gamma \left( n+1 \right)}{{{a}^{n+1}}} where \Gamma is the gamma function. My question is, do n has to be an integer number, or can it also...
  17. W

    Destructive Interference of gamma waves

    I do not understand the full theory behind destructive interference. Hence I need helps: 1. The topic on destructive (and constructive) interference was always discussed on light and sound wave. Will this theory applicable on other radiation such as gamma? 2. During two wavelenghts met at...
  18. R

    How can I obtain the gamma spectrum of an Am-Be source in MCNPX 2.6?

    Hi I want to define an Am-Be source in MCNPX 2.6 I have Neutron spectrum But I don't have Gamma spectrum of this source. Please Help!
  19. G

    How to measure the location of Gamma ray burst ?

    I have read articles about the GRB measurement using X-ray from afterglow. The article tells that the gamma ray provides poor directional information.Why? How can we use X-ray for measurement?
  20. D

    Estimating the energy of an emitted photon in gamma decay

    Homework Statement Consider a nucleus which is initially at rest and in an excited state with energy Ei. It then decays to a lower energy state with energy Ef by emitting a gamma-ray photon. Show that the energy of the photon is approximately given by Eγ≈ΔE−(ΔE)^2/(2mc^2) where ΔE = Ei - Ef...
  21. A

    Neutral pion 2 gamma decay question

    I've been reading some books on how neutral pion decay proceeds through chiral anomaly recently. What I found wired is people always use the matrix element of the axial current between vacuum and a pion as granted, saying the matrix element should be a vector and the pion momentum is the only...
  22. C

    Dirac eq gamma matrices question

    In almost all the books on field theory I've seen, the authors list out the different types of quantities you can construct from the Dirac spinors and the gamma matrices, but I'm confused by how these work. For instance, if $$\overline\psi\gamma^5\psi$$ is a pseudoscalar, how can...
  23. P

    Does relativity permit tachyons given that they have negative gamma?

    I've heard it said that relativity formally permits tachyons and that we don't believe they exist merely because there is no empirical evidence of them. However, since a tachyon's speed exceeds c, its γ must be imaginary. The t-component of the particle's 4-velocity is, depending on...
  24. W

    Identification of radiation source from gamma spectrum peaks.

    I have an unidentified radiation source. I used a NaI(Tl) detector and multichannel analyzer to collect data and plotted the spectrum. I found peaks at energies of 86.3, 123.7, and 369.6 keV. From this data I am attempting to identify the source, but I am having a difficult time. I tried using...
  25. G

    Particular Values of Gamma Function

    Hi, I would like to know why is it that gamma(1/2) = squareroot(pi) The other values as well. I don't see why out of all values that the gamma function converges to operations of pi of all things. Is there some kind of relationship to the gamma function and the trigonometric function...
  26. C

    Energy Reconstruction in Gamma Spectroscopy

    I have a question about energy reconstruction. I'm writing up a paper, and I'm trying to understand why this is the reason, before putting it in my paper. I know from experimental evidence that it is the case, though I would like to know if there is a reason. Let's say you have a sufficiently...
  27. G

    How does WolframAlpha use the gamma function to solve this integral?

    Hi I have this integral that I want to express in terms of a gamma function. Unfortunately I am unable to bring it in this form. So can you give me a hint how wolframalpha does thishttp://m.wolframalpha.com/input/?i=∫e%5E%28ix%29%2F%28ix%29%5E%281%2F5%29dx+from+-+infinity+to+infinity&x=10&y=3
  28. J

    Likelihood function of a gamma distribution

    Homework Statement Hi all, I missed the day of class where we went over likelihood functions, and I'm quite confused! For example, let's say I have n Xis, where each Xi ~ Gamma(a,b), where a and b are unknown. I want to find the likelihood function of a and b, but I don't think I really...
  29. D

    Intertial mass and determining the value of gamma

    Homework Statement This is not a problem I was assigned, I am just trying to figure out how I could prove it to myself. Basically, I am just wondering WHY the gamma value for relativistic momentum takes the form that it does, namely (1-u^2/c^2)^-.5 I've tried to prove this to myself a...
  30. alyafey22

    MHB Proof the convergence of a gamma sum

    How to prove the convergence or divergence of ? $$\sum^{\infty}_{n=1}\frac{\Gamma(n+\frac{1}{2})}{n\Gamma{(n+\frac{1}{4})}}$$
  31. L

    Understanding Gamma Matrix Logic with Clifford Algebra

    I'm reading through some notes on the Clifford algebra and at one point, the author talks about how we can break \gamma^{\mu} \gamma^{\nu} into symmetric and antisymmetric pieces and write it as \gamma^{\mu} \gamma^{\nu}=\gamma^{\mu \nu} + \eta^{\mu \nu} He then claims underneath that...
  32. B

    Is there a material that can emit gamma radiation when heated by electricity?

    Different materials emit different frequencies of radiation when heated by a source of heat such as electricity. Examples include gases and solid filaments that emit infrared, visible and ultraviolet radiation, and the scheelite calcium tungstate filaments used to produce x-rays in fluoroscopes...
  33. E

    Solving the Gamma Function: Using Recursion & Tables

    Homework Statement Questions are in picture. Homework Equations $$ \int _{0}^{\infty }x^{n}e^{-x}dx $$ = $$ Gamma (n+1) = n! $$ Gamma(P+1) $$ = $$Gamma(P)$$ $$ Gamma(P) = (1/P) $$Gamma(P+1)$$ The Attempt at a Solution 2) I have found it from table. 3) I have used recursion and...
  34. A

    Relativity question involving proofs of beta and gamma

    Homework Statement (a) The ratio v/c is very often denoted by the single symbol β. Show that if β<<1, the following are valid through terms of order β^2 E = mc^2 + (mv^2)/2 = (mc^2)[1+(β^2)/2] K = (mv^2)/2 = (mc^2)[(β^2)/2] pc = mvc = m(c^2)β γ = 1+(β^2)/2 (b) Show that if γ = ε^-1...
  35. H

    Presenilin subunit of gamma secretes

    I need to get all the information I can about it. Is their a good source for that info?
  36. N

    Behaviour of Gamma function when z = -n

    Hi there, I'm actually trying to understand why the behaviour of the Gamma function at z = -n is (-1)^n/(n!z) + O(1) The first term (although without the z) I recognized it as the residue of f when z= -n. But the rest, no idea. Any explanation is very appreciated.
  37. A

    Gamma Poisson Mixture with finite Gamma

    Dear all I am working with a Gamma-Poisson mixture distribution where (and this is not usual) the support of the Gamma distribution (in fact, I am able to restrict to the neg exponential instead of the Gamma...) is finite, e.g. [0,1]. I would like to derive the mean and a Likelihood...
  38. P

    Expected value of g(x)=1/(x+c) under gamma distribution

    Homework Statement Let g(x) = \frac{1}{x+c}, where c is a positive constant, and x is a random variable distributed according to the Gamma distribution x\sim f(x)=\frac{1}{\Gamma(\alpha) \beta^\alpha} x^{\alpha \,-\, 1} e^{-\frac{x}{\beta}}. I wish to calculate the expected value of...
  39. D

    The 'fermi Line' (the 130 GEv gamma ray signal)

    http://arxiv.org/abs/1206.1616 Strong Evidence for Gamma-ray Line Emission from the Inner Galaxy - Meng Su, Douglas P. Finkbeiner Analysis of data from the Fermi telescope shows "monochromatic" gamma ray emission at 130 GeV from the centre of the galaxy. This paper is generating a lot...
  40. Z

    How do you derive this alternate form of the gamma function?

    \Gamma(n) = int(0 to infinity)[(x^(n-1))*e^-x]dx Show that it can also be written as: \Gamma(n) = 2int(0 to infinity)[(x^(2n-1))*e^(-x^2)]dxI have no idea how to go about this. I have tried integration by parts of each to see if anything relates, but how can you get from an exp(-x) to and...
  41. A

    Finding the mle for the gamma distribution

    So if the parameter \theta is alpha... L(\theta) = \frac{1}{\Gamma(\theta)\beta^{\theta}} x^{\theta-1} e^{-x/\beta} Now I take the natural log of that... ln(L(\theta)) = ln(\frac{1}{(1-\theta)!}) + ln(\frac{1}{\beta^{\theta}}) + ln(x^{\theta-1}) + ln(e^{-x/\beta}) Now I want to...
  42. V

    Statistics The gamma distribution

    Homework Statement Find the probabilities that the value of a random variable will exceed 4 if it has a gamma distribution with (a) \alpha = 2 and \beta = 3 (b) \alpha = 3 and \beta = 4 [b]3. The Attempt at a Solution [/b} how would I even attempt this question?
  43. S

    Gamma Ray Laser, possible? Superior Weapon?

    Hello there. I am wondering if anyone can shed some light on this topic. I am searching all over the Internet to find reliable sources on the possibility of gamma ray lasers. I know that it requires an atom that can be "pumped" without spontaneously emitting its energy so it can be triggered by...
  44. J

    What is the Physical Reason for Gamma Rays Being Absorbed?

    But high frequency are absorbed, like gamma rays. I would think it would be the opposite. So what's the physical reason?
  45. H

    MHB Central Limit Theorem & Gamma Distribution

    The time it takes to complete a project is a random variable Y with the exponential distribution with parameter β=2 hours. Apply the central limit theorem to obtain an approximation for the probability that the average project completion time of a sample of n=64 projects undertaken...
  46. A

    Poisson and Gamma Distributions

    Let Y|X be a Poisson(X), and X be Gamma(\alpha, \beta). Find E(X|Y)... Since Y|X is Poisson(X), we have f(Y|X)= \frac{m^x e^{-m}}{x!}... Since X is Gamma(\alpha, \beta), we have f(x)= \frac{x^{\alpha-1} e^{-x/B}}{\Gamma(\alpha) \beta^{\alpha}}... Since f(Y|X) = \frac{f(x,y)}{f(x)} ====>...
  47. B

    How strong is gamma radiation ?

    Several elementary particles emits gamma radiation Where can I read more about the different magnitude?
  48. E

    Encyclopedia of Gamma Matrix Representations?

    Hello, I was just curious if anyone knew of a single place with a list of many different gamma matrix representations, I haven't been able to find what I want by just searching google. In particular, I'm looking for a representation of the 5+1 dimensional Clifford algera. In other dimensions...
  49. R

    K-40 Gamma Ray Branching Ratio: 10.67%

    what do u mean by gamma ray branching ratio of 'k-40' is 10.67%?
  50. iVenky

    Is gamma function derivative of factorial?

    I was searching for derivative of factorial. Many say that gamma function is the derivative of the factorial. Is that true because I searched about gamma function and it doesn't say anything like that. Thanks a lot
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