1.  Lori Rebenitsch University of Winnipeg June 17, 2014 1

2.  Neutron electric dipole moment (nEDM)  Experimental set-up  UCN counter o Requirements o Specifications Please note that captions appear in top right corner of slides! 2

3.  Baryogenesis o Baryon/antibaryon asymmetry in the early universe o Sakharov conditions (Sakharov, 1967) Baryon number violation CP-symmetry violation Interactions outside of thermal equilibrium  Standard model has small sources of CP-violation o CKM matrix - quarks o Electric dipole moment of fundamental particles  Extensions increase CP-violation  Possible EDM in neutrons due to quark structure 3

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6. 6 Graphic of planned facility UCN detector

7.  Handle rates >1.3 MHz for periods of few seconds  Reject background o Gammas o Thermal neutrons  0.05% efficiency stability  Normalize UCN density 7

8.  Based on design from PSI (Ban et. al)  Dual layered scintillating glass o Optically bonded Top layer – lithium depleted Bottom layer – lithium doped o Capture full scintillation path Right: Autodesk image of detector. Bottom: Diagram of dual layer glass and how UCN capture and scintillate. 8 Lithium glass Lightguides PMTs

9. The four points on the graph are used to find the Ramsey resonance frequency. 9

10.  DPP-PSD o Generates analysis faster than the computer o Describes signal in few variables in place of full waveform o Reduces computation load on DAQ  DAQ o Minimal computing o Saves PSD Slow control  Analyzer o Separate from DAQ o Puts data into TTree 10

11. Left: Inverted signal from Am source. Longer events are α ’s and short events are γ ’s. Right: Waveform with corresponding DPP-PSD gates. The long and short gates collect charge when open. 11

12.  By comparing the PSD variables, gamma background can be removed from data. 12 neutrons gammas Comparison of PSD Charge Integration Gates Short Integration Gate (ADC) Long Integration Gate (ADC)

13.  Environmental – long term efficiency o Glass o Temperature o Tests in progress  Pile-up o Occurs 2-3MHz between pulses o Pile-up events have Higher than average long gate value Average short gate value Can be flagged and recounted 13 Top right: Scope example of a double pulse generated from pulser. Bottom right: Rate of pile- up with respect to frequency of double pulse.

14.  UCN are produced in cycles  Number of UCN vary per cycle  Example to normalize UCN density o Utilize volume below cell for UCN density estimation o Factors Volume below cell is ~10x larger Volume presents greater probability of pile-up Throttle the UCN and/or account for pile-up 14 detector analyzer foil

15.  Detector in process of being built  Stability tests  RCNP proposal to take data with UCN spallation source this fall 15 University of Winnipeg, University of Manitoba NSERC, CFI

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