[Halld-physics] threshold Cherenkov simulation, photocathode Q.E. curves

[Eugene Chudakov]

Dear Nathan,

I enclose the input data (in the FFREAD format) for a quartz window
PMT (which is no longer available since Photonis went out of
business). Basically, it is the input for GSCKOV. There are 22 points
at different wavelengths. The 1-st 22 numbers are the photon energies
in GeV, the 2-nd - the absorption length of the window, the 3-rd - the
QE, the 4-th - the refractive index.

As I mentioned in the talk from March 2007, my GEANT simulation
produced twice more photoelectrons than people get in such
detectors. Therefore, I applied a factor of 0.5, that the N0 factor
was 50 for glass windows and 100 for quartz windows:
Npe=N0*L(cm)*sin(theta_Cher)**2.  The gas was C4F10, N-1=0.0015, so at
high energy it would be 30 p.e. for the 1m radiator and the quartz
window.

What N0 did you obtain?

Regards,
Eugene

C
C  -- optical medium  PMT XP4508 fused silica
GOPTMED22   752 22
C nm        626.       617.       612.       603.       590.       567.       553.       525.       503.       484.
C nm        457.       439.       411.       393.       347.       301.       256.       210.       187.       178.
C nm        169.       159.
        0.198E-08  0.201E-08  0.202E-08  0.206E-08  0.210E-08  0.219E-08  0.224E-08  0.236E-08  0.247E-08  0.256E-08
        0.271E-08  0.283E-08  0.302E-08  0.316E-08  0.357E-08  0.411E-08  0.485E-08  0.591E-08  0.663E-08  0.697E-08
        0.735E-08  0.777E-08
        0.100E-02  0.100E-02  0.100E-02  0.100E-02  0.100E-02  0.100E-02  0.100E-02  0.100E-02  0.100E-02  0.100E-02
        0.100E-02  0.100E-02  0.100E-02  0.100E-02  0.100E-02  0.100E-02  0.100E-02  0.100E-02  0.100E-02  0.100E-02
        0.100E-02  0.100E-02
           0.0016     0.0032     0.0053     0.0108     0.0164     0.0393     0.0684     0.1023     0.1392     0.1649
           0.1995     0.2171     0.2421     0.2424     0.2301     0.2223     0.2103     0.2056     0.1935     0.1369
           0.0296     0.0064
            0.467      0.468      0.468      0.468      0.469      0.470      0.470      0.472      0.473      0.475
            0.477      0.479      0.482      0.484      0.492      0.505      0.530      0.588      0.659      0.712
            0.794      0.943




On Fri, 20 Jul 2012, Nathan Sparks wrote:

> Hello Eugene,
>
> Could you send me the photocathode Q.E. curve that you used for the quartz PMT in your simulations? Currently in hdds there is a curve for a Cesium photocathode which looks quite different from the ones shown in your Cherenkov Simulations March 2007 talk, slide 17; the Cesium curve has low ultraviolet coverage, which may account for the smaller average number of photoelectrons seen in my simulations.
>
> Thanks,
> -Nathan
>