Upgrade of the scintillator testing station in Prague Testing station upgrade – vacuum, electronics, magnetic shielding Magnetic aspects of the measurement Electronics optimization Observed spectra – 207Bi, 137Cs, spectrometer electron beam 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Vacuum system upgrade Vacuum probe installed. Spectrometer sealed – vacuum improved from 300 Pa to 7 Pa. We have to change a hoose for further improvement. Efect of sealing on spectra is significant. 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Electronics upgrade PC controlled disriminator CAEN installed in VME – simplification of electronics, well defined and stable threshold, no possible interference between crates Independent HV sources for different PMTs – to equilibrate differences in gains. We are waiting for delivery of VME PC controlled HV modules. Cables fixation to prevent their braking on PCB. Waiting for new PC controled HV modules and repaired VME doesn‘t prevent measurement. 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

Magnetic shielding upgrade Four m-metal cylinders internal f133mm,length 305mm, thickness 1mm for PMT shielding instead of the steel cylinders which were used up to now. Plan to make a m-metal box (thickness 1mm) to cover the spectrometer completly. 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

Magnetic shielding measurement Magnetic sensor placed instead of PMT in measurement possition #1. B-field measured in 3 directions in 3 shielding configurations (no shield, steel, m-metal) for currents in the coil corresponding to the electron beam energies 0-1600keV, saturation. 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

Peak position and magnetic history Our procedure to set a certain electron beam energy: First increase the current in the coil to reach a magnetic saturation of the youk Then decrease the current to the value corresponding to the desired energy. Does the electron beam energy depend on the previously set energy due to the magnetic hysteresis? 1) If we keep the rule – first go up to magnetic saturation then go down to the desired energy 2) If we keep the rule – don‘t keep 1) if the desired energy < the original energy We don‘t observe a systematic > 1% Measured with steel shielding cylinder. 1% down 0.6% down 0.3% down 0.3% down 0.2% down Sat. 1600 1300 1000 700 300 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois Magnetic history notes

Peak position and width vs. measurement position number Does the peak position depend on the location (measurement position) of the assembly in the Black-Box due to magnetic field variations? Measured in the position #1, #2, #3, #4 and then again in #1. 1 again 1 again 1 again 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

Electronics settings optimization The optimized parameters: HV applied to the “main” PMT for the tested scintillator HV for the DE detector PMTs – we are using 2 PMTs Trigger signal length DE PMTs threshold 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

Main PMT HV optimization HV > 1400 V causes signal amplitude exceeding digitizer range. We continue to use 1300 V. Higher HV could be tried with use of an attenuator. 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

Trigger signal lenght scan We continue to use 20 ns. 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

DE-detector HV and thresholds optimization What is the best criterion? Peak/pedestal ratio Resolution Resolution error 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

Measurement conditions Threshold scans were performed for 3 different DE HV under such conditions: DE HV 1050 V E=1600 keV Vacuum 44 Pa DE HV 1100 V E=1000 keV Vacuum 6.5 Pa DE HV 1200 V E=1000 keV Vacuum 7.0 Pa Peak/pedestal ratio – DE threshold scan 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

Resolution – DE threshold scan Resolution error – DE threshold scan 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

Resolution – DE threshold scan 1D The higher is threshold the better is the ratio peak/pedestal But the measurement accuracy is worse wit higher threshold because of the statistics decrease. Peak width is not changing with the threshold. 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

Peak position – DE threshold scan Possible explanation: Higher threshold prefers the electrons which lose more energy in DE then less energy remains for the block. 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

Typical signal conditions DE left scint. block DE right Counts per 10 s deltaE left deltaE right Scint block coincidence 1439 2096 - 324 1401 405 311 2085 416 335 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Observed spectra 137Cs Pedestal = 50% of entries PMT HV 1300 V DE HV 1200 V DE threshold 10 mV Vacuum 7 Pa 207Bi Pedestal = 20-30% of entries Electron beam 1 MeV Pedestal = 2% of entries 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Summary Better achieved vacuum 7 Pa gives cleaner electron spectrum. We hope to improve the vacuum more. New PC controlled discriminator – stable, repeatable measurements. New HV modules and repaired VME crate will come soon. Not confirmed influence of magnetic field to measurements. In addition the steel mag shielding cylinders are changed to m-metal. Plan to cover the spectrometer to m-metal box. The expected upgrades don’t postpone possible measurements. The station is ready to continue scintillators characterization. 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Backup 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Observed spectra 137Cs Pedestal = 50% of entries PMT HV 1300 V DE HV 1200 V DE threshold 10 mV Vacuum 7 Pa 207Bi Pedestal = 25% of entries Spectrometer electron beam Pedestal = 2% of entries 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

Magnetic shielding measurement 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Electronics view 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Testing station setup 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Oscilloscope snap 1 DE left scint. block DE right 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Oscilloscope snap 2 DE left scint. block DE right 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Oscilloscope snap 3 DE left scint. block DE right 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Oscilloscope snap 4 DE left scint. block DE right 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Oscilloscope snap 5 DE left scint. block DE right 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Oscilloscope snap 6 DE left scint. block DE right 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Oscilloscope snap 7 DE left scint. block DE right 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Oscilloscope snap 8 DE left scint. block DE right 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Oscilloscope snap 9 DE left scint. block DE right 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Oscilloscope snap 10 DE left scint. block DE right 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Oscilloscope snap 11 DE left scint. block DE right 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois

V. Vorobel, SuperNEMO meeting, Aussois Oscilloscope snap 12 DE left scint. block DE right 15.1.2014 V. Vorobel, SuperNEMO meeting, Aussois