- 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.
- acceptance corrections
- efficiency estimations
- inefficiency corrections
(don't care conditions)
- initial set of masks
- 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.
- 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"
- It becomes more sensitive to the background or
noise triggering and has to be experienced from the
raw data analysis.
- 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.
- All spectra obtained contained both, vertex-pointing
candidates and upstream track signatures which can be
programmed for veto decision.
- 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.
- Fit for an experimental momentum distribution
obtained during the so-called "transparent run" with
minimum bias conditions
- 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
- Uniform random generator test
- Particle emission
- Tagging the particle through the active detector
material (geometry validation)
- Dead material effect studies
- Masks bookkeeping
- Plot histogrms
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