Development of the BST pad system

"Monte Carlo studies."

Under construction

  1. The BST trigger principle requires primary knowledge about particle tracks. Their predominant signatures have to be included into some algorithm for the furhter online recognition.
    1. acceptance corrections
    2. efficiency estimations
    3. inefficiency corrections (don't care conditions)
    4. initial set of masks
  2. The typical mask can be written as "1234", where the digit position corresponds to a certain plane a the value is a ring number where the signal occured. The mask can be represented as: 1000*Ring(in 1st plane) + 100*Ring(in 2nd plane) + 10*Ring(in 3rd plane) + 1*Ring(in 4th plane) Ring = 0...8 and 0 means no signal registered.
  3. Requiring 3 hits per track only one can write a number of permutations for a given mask: x234, 1x34, 12x4, 123x The symbol "x" here expresses the don't care condition for the trigger logics and it should compensate a single plane inefficiency. For example:
    0000000X 00000010 00000100 00001000 "x234"
    00000001 000000X0 00000100 00001000 "1X34"
    00000001 00000010 00000X00 00001000 "12X4"
    00000001 00000010 00000100 0000X000 "123X"
  4. It becomes more sensitive to the background or noise triggering and has to be experienced from the raw data analysis.
  5. The full Pad detector information is latched in the front-end for a few randomly chosen HERA bunch crossings and then transmitted to the VME interface and written on the tape.
  6. All spectra obtained contained both, vertex-pointing candidates and upstream track signatures which can be programmed for veto decision.
  7. Track curvature in the homogenious torroidal magnetic field is a helix described in terms of 5 variables (R, w, t, phi0, Vz):
    x=R*(cos(wt + phi0 - Pi/2) - cos(phi0 - Pi/2)),
    y=R*(sin(wt + phi0 - Pi/2) - sin(phi0 - Pi/2)),
    z=Vz*t,
    R, w and Vz are physical parameters and t and phi0 are arbitrary chosen values:
    R[m]=P[GeV/c]*sin(theta)/0.3B[T],
    Vz=c*cos(theta)*sqrt(1 - (E0/E)2),
    w=Vt /R=(c/R)*sin(theta)*sqrt(1 - (E0/E)2),
    where "E0" - is a particle energy in the rest frame and "theta" - is a scattering angle. Finally (x, y, z) = F(E, P, theta, phi0, t) which reduces to F(E, theta, phi0, t) for relativistic particles because P=E/c. The "phi0" corresponds to an azimuthal scattering angle of the particle in a beam coordinate system.
  8. Fit for an experimental momentum distribution obtained during the so-called "transparent run" with minimum bias conditions
  9. gamma>50 keV (smaller energies are thought to be absorbed in the beampipe) e, mu, pi, p, can't be separated because all they are minimum ionizing particles
  10. Uniform random generator test
  11. Particle emission
  12. Tagging the particle through the active detector material (geometry validation)
  13. Dead material effect studies
  14. Masks bookkeeping
  15. Plot histogrms


Working over the night