June 10, 2003
Tests with micromegas and resistive foil made in Saclay:
Fe55 spectrum, gain vs voltage.
Layout of PCB.
New TPC results:
X resolution vs phi, drift
distance, distance to edge;
Z resolution vs drift distance for P10, ArCO2;
Cuts made on data for above plots;
Drift vs sigma for P10, ArCO2,
February 20, 2003
Very first plot from
a test cell with micromega and resistive foil.
February 13, 2003
First plots from
test cell with 1 MOhm/sq resistive foil.
January 16, 2003
TPC with Fe55 source
A very simple analysis. The group with the largest amplitude in the event is
the seed. This amplitude must be larger than 2 ADC counts (otherwise the cluster
amplitude is set to -1). Groups that have no pad with a distance of less than
3.5 mm to the seed must have amplitudes less than 2 ADC counts (otherwise the
cluster amplitude is set to 0). The cluster amplitude is the sum of the amplitudes
of all groups with pads within 3.5 mm of the seed. This plot shows
the distribution of the cluster amplitude. In the lower plot the background distribution
(points) is added with arbitrary normalisation. The background distribution is
from random triggered events without source.
New determination of T0, change of amplitude calculation.
First the time TMax of maximum pulse is determined.
The amplitude at TMax is calculated from the average
pulse between TMax+50 and TMax+350 (if the upper bound
is out of range the window is reduced). The scalefactor
is calculated using the fall times determined from a
previous calibration run (pulse fit) assuming an exponential
drop of the pulse (pulse(T) = A * exp( (TMax-T)/FallTime)).
The new T0 is at the rising shoulder of the pulse where
pulse(T) = A/2. Using linear regression a line is determined
as an approximation of the rise with a window of 30 time
bins and line(T0) = A/2.
Finally the amplitude is corrected from TMax to T0: A_T0
= A_TMax *exp(TMax-T0).
With this calculation the T0 and amplitude are very close
to the values determined from a fit. These histograms are equivalent to the old comparison. You can look also at the new scatter plots.
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