1. Test of 1kg point contact detector and CDEX-1 Data Analysis Process Wu Yucheng CDEX collaboration 2016-6-29 Development of High Purity Germanium Detector Techniques for Applications in Fundamental Research @ Universitaet Tuebingen

2. Outline System Setup System Performance Data Analysis Summary 2 Detector Shielding Electronics Energy linearity (Calibration) Energy resolution Decays of characteristic X-rays Data quality check Background & Microphonics Cut Physics Interpretation

3. System Setup: Detector 1kg-PPCGe (Canberra 2010.12) 1kg (Φ62.2×62.3, 187cm 3, 994g) Dead Layer: < 0.5mm/Ge (Canberra) P-type Crystal P + Point Contact (few mm, few pF) HV: +3500 V Pulsed Optical Reset preAMP (P + Contact) RC Feedback preAMP (N + Contact, HV module) Cryostat: OFHC, 1.5mm Dewar: 30L (LN 2 Holding time – 14 days) 3

4. System Setup: Shielding System 4 PE Pb PE(B) Cu Rock  PE  Pb  PE(B)  Cu CJPL 2400m1m20cm

5. System Setup: Electronics Systematic Setup 5 1kg-PPCGe Pulsed optical feedback Preamplifier Spec AMP Discriminator Logic Random Trigger Pulser FADC VME BUS PC Trigger VME Crate NIM Crate Resistive feedback Preamplifier Timing AMP HV Supply 6μs/12μs 10ns(int.) Spec AMP 2μs Fast Pulse Slow Pulse S1 S2

6. Energy Linearity 6 System Performance: Energy linearity SourceE /keV RT0 152 Eu121.78 152 Eu344.28 152 Eu778.90 152 Eu867.37 152 Eu964.08 152 Eu1408.1 SourceE /keV RT0 68, 71 Ge1.299 65 Zn8.979 68, 71 Ge10.367 SourceE /keV RT0 152 Eu121.78 152 Eu244.70 152 Eu344.28 SourceE /keV RT0 152 Eu121.78 152 Eu244.70 152 Eu344.28 152 Eu778.90 152 Eu867.37 Below 12 keV: Intrinsic Background; 0.3 – 3 MeV: 152 Eu sample.

7. System Performance: Energy resolution Energy Resolution 7 8.5 keV @ 964.08 keV 246 eV @ 10.37 keV

8. System Performance: X-ray Decay 8 Cosmogenic isotope:Lifetime” 68, 71 Ge:K-shell EC X-ray : 10.37 keV 68 Ge: 270.8 day L-shell EC X-ray : 1.29 keV 71 Ge: 11.43 day

9. Data Analysis: Data Quality Check 9 S1 S2

10. Data Analysis: Physics Interpretation Elastic scattering 10 θ Center of mass frame WIMP Target ERER E a.Earth velocity relative to dark halo b.Quenching factor: nuclear VS electron recoil c.Form factor d.Energy resolution and threshold of detector e.Spin: dependent VS independent f.Mixed components J. D. Lewin and P. F. Smith, Astrop. Phys. 6 (1996) 87 a,b,d,fc,e,fe,f M χ = 10 GeV, σ = 10 -40 cm 2

11. Data Analysis: Physics Interpretation With WIMP signal Maximum Likelihood Method Without WIMP signal Maximum Gap Method Binned Poisson Method Conservative! 11 G. Savage, et al, JCAP. 04 (2009) 010

12. Data Analysis: Physics Interpretation 12 Predicted Anti-Compton Surface/Bulk

13. Summary 1kg-PPCGe has been set up System performance is good Energy Linearity; Energy resolution; Threshold; Decays Data analysis is processing Quality check  Background subtraction  Physics interpretation Optimistic physics result 13

14. Thanks for your attention! Questions and Comments … 14