Select Km22 monitor sample and measure the average ADC counts in each layer.
To convert the ADC counts to the actual energy deposit in each layer,
one needs to have an estimate energy deposit in each layer for Km22 sample.
From the Monte Carlo simulation, one can generate the Km22 sample with a proper
beam profile. Assuming the Km22 trigger is well simulated, one can then derive
the so-called RS calibration constants from
rd_cal = <ADC>/E_mean(UMC)
and
E_layer = ADC_layer /rd_cal
Where E_mean(UMC) is the mean energy in each RS layer. In addition to the
trigger, the beam profile and the dip angle can affect this value since velocity
of particle penetrating each RS layer and effective energy deposit in each
RS layer may vary. The average of ADC counts <ADC> can also be
affected by accidental hits, especially in the environment of high rate. In
PNN1 data analysis, this contamination can be either prevented by switching
to TD energy (if the timing of accidental hit differs from the track time)
or removed by applying a so-called RS dE/dx cut (if the timing of accidental
hit is very close to the track time).
Apparently, the energy deficit in the target and IC keeps unchanged and
is well simulated by Monte Calro. However, one does see a significant deficit
in RS, completely accounting for the total Kp21 energy deficit.
3. The energy deficit in each RS layer
1) in piscat monitor sample (plot). The selection criteria are
if(ptot.lt.100.or.ptot.gt.300)return
if(nhz.lt.5)return
if(abs(cos3d).gt.0.5)return
if(pr_rf.lt.0.02)return
if(ntr_d.ne.1)return
if(ext(2))return
if(ext(4))return
if(abs(deltarp/sig_p).gt.3)return
if(ipiflg.ne.0)return
if(b4abm.gt.1.2)return
if(tpi-tk.gt.2)return
if(.not.l12)return
if(.not.lhex)return
if(itgqualt.gt.1)return
Both piscat and km21 samples show a consistent energy deficit in the RS
inner layers. But the energy deposits in the outer layers have a trend to
increase. By checking the dip angle and the stopping z position, one can find a clear difference
between piscat and Km21 sample. Requiring 0.3<|cos3d|<0.5, layv4=18
and |zf|>30 cm for the piscat sample, one gets a very similar plot as that shown
for the km21 monitor sample.
4. Empirical correction and consistency check
Applying the correction factors given by the piscat monitor analysis to the
Kp21 monitor, the peak energy becomes 105.2+/-0.1 MeV,
close to what we have for the 1998 data. Using UTC measurement to give the
predicted RS energy, namely
Ers(UTC) = sqrt((pdc-1.3)**2+139.57**2)-139.57
and
Deltar_Ers = Ers(UTC) - Ers
one has Deltar_Ers = 1.1 +/- 0.1 MeV (see the
plots for this correction). There is still a disagreement
between
the UTC prediction and the RS measurement.