Recent content by 1a2

  1. 1

    Use FMM or FFT for low-discrepancy sample of atoms?

    To complete my Master's thesis, I am working on a problem that deals with an arrangement of initial atoms, and their positions are then changed according to a pseudo-random number generator with low discrepancy. My advisor told me that instead of computing the interactions between the atoms for...
  2. 1

    Computing Cherenkov angle when only knowing n?

    so when vp→c? But then that gives beta→1 and thus cos(θc)→1/(1*n) so for n=1.001, 1.01, 1.03, 1.07, 1.12, 1.33, 1.50, θc = cos-1(1/n)?
  3. 1

    Computing Cherenkov angle when only knowing n?

    so the max angle occurs when beta→∞. But beta = vp/c, so vp→∞ So we should just set vp→∞ for each of the values for n? The problem asks for the angles, not vp values
  4. 1

    Computing Cherenkov angle when only knowing n?

    the max angle is 90 degrees, right? That occurs when cos(thetac) = 0 ⇒ vem = vp? I don't understand how finding the maximal angle is related to the Cherenkov angle
  5. 1

    Computing Cherenkov angle when only knowing n?

    so how am I supposed to solve for the Cherenkov angle then, if we can't obtain vp and beta? Should I ask the instructor for a hint or more clarifiation?
  6. 1

    Computing Cherenkov angle when only knowing n?

    Here is the exact problem statement: Calculate the Cherenkov angle and the threshold momentum for media with n=1.001, 1.01, 1.03, 1.07, 1.12, 1.33, 1.50 for electrons, muons, pions, kaons, and protons
  7. 1

    Computing Cherenkov angle when only knowing n?

    Homework Statement If all we know is that the media is 1.001, how can we compute the Cherenkov angle and threshold momentum of electrons,muons, pions, and kaons?Homework Equations I know that cos(theta_c) = 1/beta*n, where beta = v_p/c and n=c/v_em, where v_p is the particle velocity and v_em...
  8. 1

    Calculating range of muons in a detector?

    Homework Statement If one can approximate NOvA detectors being built out of hundreds of "sandwiches" or PVC plastic of 1cm thickness and a "plane" of oil of 5.6 cm, what is the range of muon of energy 200MeV, 500MeV, 1GeV, and 1.8GeV in the detector? Homework Equations \frac{dE}{dρ*x} =...
  9. 1

    Time of flight experiment to distinguish muons from pions?

    I know that to distinguish electrons from muons, we can use the time of flight method. We can determine the time if the momentum is known. We can measure the momentum can be done by mounting a magnet on the way of particles, and the muons and electrons will be bent with the same curvature since...
  10. 1

    Time of flight experiment to distinguish muons from pions?

    If I wanted to design an experiment which would allow to distinguish muons from pions in the energy range from 200 MeV to 2 GeV, how would I do it in a simple way? Could I just use the Time of Flight experiment? What quantitative arguments can one make for the design of the detectors?
  11. 1

    IV curve for voltage across shunt for probe current (Helimak experiment)

    Homework Statement Let's say I have a Langmuir probe I-V characteristic from the Helimak experiment. The plasma ions are singly ionized argon. The probe has an effective area of 0.000016 m^2. Estimate the floating potential, electron density, and temperature. Based only on the nature of the...
  12. 1

    Instruments to measure plasmas besides Langmuir probes?

    To be more specific, the plasma has a density <5x10^19/m^3 and 10eV temperature. I was thinking either capacitive probes as, depending on the design, these can work in hotter/denser plasmas than Langmuir probes. They are really just a Langmuir probe without an exposed metallic tip when it...
  13. 1

    Radiated power of electron in fusion device?

    Homework Statement Some time ago, an (in)famous paper by Trubnikov argued that magnetic fusion would be impossible because the power radiated by electrons would exceed any likely fusion power. He provided a very elaborate calculation, but the result was not greatly diffferent from the simple...
  14. 1

    Instruments to measure plasmas besides Langmuir probes?

    If a plasma is created at one end of a solenoid and heads down towards a target with a density and temperature too high for Langmuir probes, what other instruments can measure the density with a strong signal that is easy to interpret?
  15. 1

    Questions about the observations from NIF at LLNL

    The NIF (http://en.wikipedia.org/wiki/National_Ignition_Facility) is an experiment at the LLNL, using a 'target' filled with D-T in order to create nuclear fusion reactions. I was wondering what would be a way to examine the light emitted from the imploded plasma target there, what colors could...
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