AIDA
GELINA
BRIKEN
nToF
CRIB
ISOLDE
CIRCE
nTOFCapture
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EDI_PSA
179Ta
CARME
StellarModelling
DCF
K40
nToF
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Entry time:
Fri Mar 28 20:47:53 2025
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> > Check RAL108 +/-15V PSU > > Measured output voltages +15.21V -15.18V - OK > > Observe output voltages with DSO ( ch #1 AC/1M +15V, ch #2 AC/1M -15V ) - see attachments 1 & 2 > > What we should observe is c. 1mV rms ( white ) noise but we clearly observe similar noise transients ( c. 60us period with HF structure ) to those observed at RAL108 > outputs. The RAL108 preamplifier units do have RC filters on the +/-15V - typically c. 100 Ohm and 4.7uF. Some additional, inline filtering with a lower rolloff > frequency may be required. > > > > > Observe c. 2mV p to p noise with DSO ( Z_in = 50 Ohm ) c. 60us period with HF structure. DSO connected to junction box via 34-way IDC - 16x Lemo-00 adaptor. > > > > Origin of noise upstream of 4x34-way to 8x16-way Junction Box. Not microphonics from Edwards RV5 Rotary Pump. > > No change observed with simple ground connections between NIM bin/+/-15V PSU/Junction Box and MSL type W1 preamplifier units/vacuum chamber/support assembly. > > > > > > Estimate of electronic noise > > > > Pulser BNC PB-5 > > > > Amplitude 0.5V > > Attenuation x1 > > Decay time 1ms > > Frequency 50Hz > > > > Preamplifier RAL108 > > Output impedance 100 Ohm > > Sensitivity 20mV/MeV ( into high Z load ), 6.7mV/MeV ( into 50 Ohm load ) > > > > Amplifier EG&G Ortec 571 > > Input terminated by 50 Ohm > > Gain x1 (internal) x 1.0 (fine gain) x 50 (coarse gain ) = 50 > > Shaping time 0.5us > > > > MCA Amptek 8000D > > Input FSR 10V > > 12 bit ADC > > > > > > Nominal gain = 6.7mV/MeV x 50 = 335mV/MeV > > > > 12 bit ADC input FSR = 10V / 0.335V/MeV = 29.85MeV FSR or 7.3keV/channel > > > > > > dE p+n junction strip # 4 ( of 0-15 ) > > > > pulser peak centroid = 799.8 ch > > pulser peak width = 7.8 ch FWHM = 57 keV FWHM > > > > > > E p+n junction strip # 4 ( of 0-15 ) > > > > pulser peak centroid = 864.8ch > > pulser peak width = 3.5 ch FWHM = 26 keV FWHM > > > > > > E n+n Ohmic strip # 4 ( of 0-15 ) > > > > pulser peak centroid = 913.0 ch > > pulser peak width = 5.3 ch FWHM = 39 keV FWHM > > > > > > Noise estimates are probably accurate to c. 10% level.
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