AIDA
GELINA
BRIKEN
nToF
CRIB
ISOLDE
CIRCE
nTOFCapture
DESPEC
DTAS
EDI_PSA
179Ta
CARME
StellarModelling
DCF
K40
BRIKEN
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> Optimization of ADC thresholds > > In order to try to reduce the grass-like background > we make a finer adjustment of individual ADC thresholds. > We make first a control measurement putting the 252Cf source > in the center of the detector (AIDA removed) > Start: - > Stop: 23:55 > File: 161009_2355_252Cf_control.root > > We then make an adjustment of thresholds one ADC at a time. > We adjusted the threshold so that the very low amplitude noise height > in the spectrum is only a small fraction of the pulser. > > New configuration file: 160718Conf_BrikenFull_test02_thr.xlsx > > A verification measurement with 252Cf > Start: 01:55 > Stop: 02:09 > File: 161010_0209_252Cf_newthr.root > > > And the leave a background measurement overnight: > Start: 02:12 > Stop: 07:12 > File: 161010_0712_bck_newthr.root > > We compare the grass-noise rates now with the rates before threshold adjustment > For that we integrate the BRIKEN spectrum between 900keV and 1.5MeV > The rate before was 0.085 counts per second per MeV > The rate now is 0.039 counts per second per MeV > So the improvement was only a factor 2. > > One can try to set the thresholds higher however with this rate the probability > of having a noise signal in a 0.5ms window after a beta signal will be about 1E-5. > > The plots below show the situation before and after.
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