What is Gamma: Definition and 711 Discussions

Gamma (uppercase Γ, lowercase γ; Greek: γάμμα gámma) is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop /ɡ/. In Modern Greek, this letter represents either a voiced velar fricative or a voiced palatal fricative.
In the International Phonetic Alphabet and other modern Latin-alphabet based phonetic notations, it represents the voiced velar fricative.

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  1. Ryan_m_b

    Reflecting Gamma Rays w/ Electron Gas for Spacecraft

    In a discussion recently I came across the idea of an antimatter photon rocket, to quote http://en.wikipedia.org/wiki/Nuclear_photonic_rocket#Power_sources" Looking through various sites via google I've had a few answers as to how gamma rays may be reflected, the general consensus is that it...
  2. A

    Compton Scattering given Energy of Scattered Gamma.

    Homework Statement Gamma rays of energy 1.02MeV are scattered from electrons which are initially at rest. Find the angle for symmetric scattering at this energy. What is the energy of the scattered photon from this case? Homework Equations \Delta \lambda = 0.0243A (1 - cos \theta )...
  3. M

    Model parameter distributions from Gamma distributed data

    I have a set of data points {xi,yi} where each yi is a Gamma distributed variable where both the shape k and scale \theta depend on i. I then fit the data points with a power law model y=a(x)b. I would like to know the probability distributions for the fit parameters a and b. Is...
  4. M

    Does a gamma ray photon have less energy than a radiowave photon?

    I'm wondering because the gamma ray photon is smaller yet it has a higher frequency. Is it because the amount of energy that passes a single point in a second for a gamma ray is higher than that of radio waves, since a lot more photons are passing that single point that in other em radiation?
  5. Simfish

    Do nearby gamma ray busts/supernova damage *more* than just the ozone layer?

    http://en.wikipedia.org/wiki/Near-Earth_supernova So we know that many people are putting hard constraints on the galactic habitability zone based on the presence of nearby supernova/gamma ray bursts. But if they *only* affect the ozone layer, then I doubt that it's as hard of a constraint as...
  6. N

    Can Gamma Radiation Be Deflected by Matching Frequencies of Ionized Radiation?

    I am very uneducated in physics, however I did take a remote sensing course in college where we discussed EMR. My questions are the following: could gamma radiation be absorbed in a material and then transferred to another material or dispersed. I know that gamma radiation has no charge and is...
  7. B

    Calculating Incomplete Gamma Function for Complex Arguments

    How do I calculate the integral \int_{ix}^{i\infty} e^{-t} t^{-s-1}dt, where x>0, s>0? Mathematica gives \Gamma(-s,ix), where \Gamma(\cdot,\cdot) is the incomplete gamma function, but I am not sure how to justify this formally.
  8. O

    Chi-squared inverse function and incomplete gamma function

    is there a way to explicitly express the chi-squared inverse function? when programming it, I have had to resort to a guessing system where I find a chi value that is too low and too high, and evaluate the chi-squared CDF to reset the high and low points iteratively until it is within a...
  9. E

    An arithmetic gamma function?

    In some exercises I've stumbled upon a function which is denoted \gamma_{m}(n) with m,n natural. I've no idea what is the definition of the function and could not infer from the exercises. Searching google yielded nothing, as it kept suggesting me the OTHER Gamma function. Can anyone here help...
  10. N

    Proving analyticity of gamma function

    Hello, In our course of complex analysis we proved that the gamma function, \Gamma(z) = \int_0^\infty t^{z-1} e^{-t} \mathrm d t for 0 < Re(z), is analytical. We did this by defining f_{\epsilon,R}(z) = \int_\epsilon^R t^{z-1} e^{-t} \mathrm d t about which we can prove that it is analytical...
  11. T

    Gamma and Beta Integrals

    Homework Statement The Gamma and Beta integrals are defined respectively as \Gamma (z) = \int^{\infty}_0 t^{z-1} e^{-t}\;dt B(p,q) = \int^1_0 t^{p-1} (1-t)^{q-1}\;dt. Determine for what values of the complex parameters z, p, q the integrals converge absolutely and explain why. The...
  12. bcrowell

    Dark matter: gamma rays, direct detection, and solar-system tests

    Here are some recent papers on attempts to detect dark matter directly or indirectly: a solar system test with a possible positive result: http://arxiv.org/abs/1001.1697 direct detection, with seemingly contradictory results: http://arxiv.org/abs/1106.1066 via gamma-ray astronomy...
  13. Peeter

    Otimes notation and tau matrices used in definition of gamma matrices?

    In Zee's Quantum Field theory book he writes \begin{align}\gamma^0 &= \begin{bmatrix}I & 0 \\ 0 & -I\end{bmatrix}=I \otimes \tau_3 \\ \gamma^i &= \begin{bmatrix}0 & \sigma^i \\ \sigma^i & 0\end{bmatrix}=\sigma^i \otimes \tau_2 \\ \gamma^5 &=\begin{bmatrix}0 & I \\ I & 0\end{bmatrix}=I \otimes...
  14. H

    Clement Desmorme's experiment for Adiabatic Index gamma

    Homework Statement Basically the experiment itself can be found in here: http://www.ce.tuiasi.ro/romana/publicatii/cursuri/radinschi_fizica/Lab2%20engleza.pdf or here: http://blog.cencophysics.com/2010/02/clement-desormes-experiment/ The experiment and all the necessary calculations...
  15. M

    Exploring Gamma Photon Distribution in the Galaxy: What Can We Learn?

    How many gamma photons are in the galaxy, and what can we know about the distribution? Which kind of process can absorb them?
  16. V

    SR: Gamma rays creating election-positron pair

    Homework Statement This is a special relativity question: Two gamma rays of identical energies E collide with an angle \theta between their velocities. Show that positron-electron pair creation is impossible in the limiting case \theta=0. Find the minimum \theta value for p-e creation to...
  17. A

    Simple gamma matrices question

    Hi I've just read the statement that a matrix that commutes with all four gamma matrices / Dirac matrices has to be a multiple of the identity. I don't see that; can anyone tell me why this is true? Thanks in advance
  18. L

    Project: Detect Gamma Rays with Cesium & Geiger Counter

    Hi, I need to make a project to demonstrate Gamma rays. I have cesium as a source to use and a geiger counter to detect gamma rays. Ideas are welcome!
  19. J

    About the missing Gamma Rays of Low Energy Fusion

    Hello Guys, I have some questions relating to Cold Fusion / Low Energy Fusion. It seems Gamma Rays are not present from Cold Fusion experiments and Neutrons cannot be seen released from a sonar luminance reaction within the same nanosecond of time as the Alpha Process Completes...
  20. C

    Gamma matrices and projection operator question on different representations

    Typically I understand that projection operators are defined as P_-=\frac{1}{2}(1-\gamma^5) P_+=\frac{1}{2}(1+\gamma^5) where typically also the fifth gamma matrices are defined as \gamma^5=i\gamma^0\gamma^1\gamma^2\gamma^3 and.. as we choose different representations the projection...
  21. C

    Gamma matrices projection operator

    Typically I understand that projection operators are defined as P_-=\frac{1}{2}(1-\gamma^5) P_+=\frac{1}{2}(1+\gamma^5) where typically also the fifth gamma matrices are defined as \gamma^5=i\gamma^0\gamma^1\gamma^2\gamma^3 and.. as we choose different representations the projection...
  22. L

    Exploring Gamma Rays in the Classroom

    I need to do a presentation to teach the rest of my class about Gamma rays. We need to do some sort of experiment to demonstrate Gamma Rays. Any ideas?
  23. E

    Cause of Bump in Uranium Gamma Spectrum

    Homework Statement What is the cause for the bump in the lower energies of this spectrum: http://en.wikipedia.org/wiki/File:Gammaspektrum_Uranerz.jpg The Attempt at a Solution Is it just normal Compton? I'm doubting that because that is very asymmetric. I can't find anything in any textbook I...
  24. J

    Need reference or derivation of Gamma function for half-integer orders

    Hi all, I'm looking at the http://en.wikipedia.org/wiki/Gamma_function#General" for the gamma function, and it lists equations for the gamma function of half-integer orders (i.e. gamma(0.5+n) and gamma(0.5-n)). But, it doesn't list a reference as to where this equation comes from. Does...
  25. S

    Gamma Function on negative Fractions

    Gamma Function on negative Fractions! If we take a look at the Gamma Function and evaluate the integral by parts then we will get infinity in the first step of Integration by Parts eg: Integral e^-1*x^-5/3 Limits being 0 to Infinity as usual! If we try to integrate this we will get...
  26. J

    Solving Gamma Function Homework: Get Help Now

    Homework Statement In attachment The Attempt at a Solution I can't see the link in the steps, a little help pls.
  27. Z

    An identity about Gamma and Riemann function

    we know that \Gamma (s)= \int_{0}^{\infty}dxe^{-x}x^{s-1} however every factor of the Riemann Zeta can be obtained also from a Mellin transform \int_{0}^{\infty}dxf(x)x^{s-1} =(1-p^{-s})^{-1} where f(x) is the distribution \sum_{n=0}^{\infty}x \delta (x-p^{-n}) is there any...
  28. I

    Will a faraday cage stop gamma rays?

    Can a faraday cage be used to stop the radiation at the Japanese reactor? If not why not? I know the frequencty is high but what if you pulsed DC current at the same frequency would that stop it?
  29. daisey

    Gamma Radiation: How Does It Pass Through & Damage the Body?

    Question about Gamma Radiation. I understand that Gamma Radiation, like X-Rays, are just photons (light particles) at different frequencies. I was reading an article about the Nuclear Plant problems in Japan, and the article stated that photons from Gamma Radiation for the most part pass...
  30. G

    Finding the Gamma Distribution of X1+...+Xn

    Homework Statement Let X1,...,Xn be independent, identically distributed random variables with exponential distribution of parameter λ. Find the density function of S = X1+...+Xn. (This distribution is called the gamma distribution of parameters n and λ). Hint: Proceed by induction...
  31. P

    Can Gamma Rays & Other Electromagnetive Waves have particle's characteristics?

    It's known that light can have particles characteristic in a particular condition.
  32. S

    Can High Energy Gamma Rays Interact with Protium and Heat It Up?

    Hi All, How can a high energy (above 1 MeV) gamma ray interact with a protium (hydrogen with only a proton in nucleus)? Does it only ionize it? Does it break it up? Does a chain reaction occur where antiparticles are formed and then annihilated, spitting out another gamma ray? I've been...
  33. M

    Gamma ray coincidence and multipoles

    Dear Physics Forums, I am currently conducting an experiment on gamma ray coincidence from Co-60. Co-60 decays to an excited state, then de-excited by emitting two gamma rays. The aim is to deduce the angular momentum L of the first excited state. Apparently L indicates the type of...
  34. L

    Solving Gamma Function Int xe^-x^3 from 0 to Infinity

    Homework Statement \int xe^{-x^{3}}dx from 0 to infinity Homework Equations \Gamma = \int x^{p-1}e^{-x} from 0 to infinity The Attempt at a Solution my problem is I'm not sure what i am supposed to do with the exponent of 3 on the e, because it seems to affect the answer...
  35. L

    Integrating $\frac{x^{1-\epsilon}}{x+c}$ to Evaluate I(c) with Gamma Functions

    Consider I(c)= \int_0^\infty \frac{x^{1-\epsilon}}{x+c} dx For what values of \epsilon are these integrals convergent? Would it be \epsilon \geq 0? Then I'm asked to use x^{-\lambda} \Gamma(\lambda) = \int_0^\infty d \alpha \alpha^{\lambda-1}e^{-\alpha x} for x>0 and the identity...
  36. L

    Gamma Rays: Finite Range in Water?

    i was told that high emergy gamma rays had a finite range in water. how can this be if they are both massless and chargeless. is it because they are absorbed/produce electrons/positrons thanks
  37. L

    Gamma - when is pair production dominant

    hi, am i right in saying that for gamma rays of energies above 10MeV, the main interaction mechanism is pair production? and this is independent on energy? (or is it compton scattering for example?) thanks
  38. Saladsamurai

    Differential equation: I think there is a Gamma Function here

    ***Please skip ahead to post # 6 where I have better formulated my question. Thank you! *** I have an equation AY'' + B\eta^2Y'=0 \qquad(1) where A and B are known constants and Y is a function of η. By using the substitution X = Y' I have reduced the problem to a first order ODE of...
  39. S

    Is There an Equation to Determine Gamma Ray Frequency from Radioactive Decay?

    Readers, Hi, I'm new here, and have a question that has piqued my interest, and have not found a solution elsewhere. My question is as such: is there an equation to determine the energy or frequency of the gamma ray emitted as a byproduct of radioactive decay for a given isotope...
  40. T

    Annihilation of Electron by Positron to Produce at least 2 Gamma Rays

    Homework Statement The problem is listed as follows: Show that conservation of energy and momentum require at least two gamma rays to e emitted in the annihilation of an electron by a positron. Homework Equations p(initial) = p(final) E(initial) = E(final) Total rest mass = 1.0218...
  41. V

    Physics - Calculating gamma

    Homework Statement Homework Equations γ = Cp/Cv ε = W/Qh PiVi^γ = PfVf^γ The Attempt at a Solution I know I have to find the gamma firstly in order to determine what type of gas is present here. And to do that I have to pick one of the adiabatic processes. I chose to do AD. But I am...
  42. H

    Is the Gamma Function Equal to Its Simplified Form?

    Hello, I need help proving this: http://mathworld.wolfram.com/images/equations/GammaFunction/Inline177.gif = http://mathworld.wolfram.com/images/equations/GammaFunction/Inline179.gif
  43. G

    Protection from both beta particles & Gamma rays?

    What would be the best protection from these two at the same time? Lead alone or a mixture of something like lead and Plexiglas?
  44. A

    Thermodynamics, meaning of gamma

    Hey guys, I just had a conceptual question as to the meaning of gamma in thermodynamics. I mean, I know that gamma = cp/cv, where cp = at constant pressure the amount of heat to raise one kg of substance 1 degree, and cv = amount of heat to raise one kg of substance 1 degree at constant volume...
  45. M

    Deriving properties of the Gamma Function

    I was just curious as to how I can show the following properties of the Gamma Function, they came up in some lecture notes but were just stated? Notation: G(z) = Gamma function 2^(z) = 2 to the power of z I = Integral from 0 to infinity (1) G(z)*G(1-z) =...
  46. A

    Integration of incomplete gamma function

    Hi, I am interested in performing the following integration: \int _{-\infty }^{\infty }\Gamma\left[k,\frac{x+u}{v}\right]e^{-\frac{(x-m)^2}{2\sigma ^2}}dx . I would appreciate anyone's help. I have been trying to do it in Mathematica but it runs out of time returning the same integral...
  47. W

    Gamma as a Jacobian of Lorentz transformations

    Hello. When one is converting between coordinate systems, the Jacobian arises as a necessary consequence of the conversion. Does this occur with transformations between relativistic systems, and, if so, is this manifested through the prevalence of gamma in the transforms? Any guidance would...
  48. J

    How is the Gamma function used in solving for the expectation value of momentum?

    Homework Statement
  49. A

    Why Gamma Ray Emission Has No Change in A or Z?

    Why in gamma ray emission there is no change in A or Z ? We know that in Alpha decay 2 protons and 2 neutrons are subtracted from the element. and in Beta decay there is change in atomic number by + or - 1. but why there is no any change in Gamma Decay in mass number A or atomic number. i...
  50. K

    How to show gamma matrices are unique?

    In most of the physics textbooks I read they only give one or two representations of gamma matrices, but none gives a proof, so how can I prove it from the Clifford algebra?
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