The KATRIN experiment

Transcription

1 The KATRIN experiment Status and SDS comissioning Philipp Chung-On Ranitzsch for the KATRIN collaboration Insitute for Nuclear Physics, Westfälische Wilhelms-Universität, Münster

2 The KATRIN experiment 2 Outline Introduction MAC-E filters and the KATRIN experiment Commissioning of the Spectrometer and Detector Section (SDS) Electron optics Background Conclusion

3 The KATRIN experiment 3 (Tritium) β-decay and neutrino mass β-decay: A A Z X N Z+1 X N 1 + e +ν e Tritium 3 H: E 0 = 18.6 kev T 1/2 = 12.3 y Rhenium 187 Re: E 0 = 2.47 kev T 1/2 = y dn de = K F(E, Z) p E ( e + m e )( E 0 E e ) ( E 0 E e ) 2 m( ν e ) 2

4 The KATRIN experiment 4 MAC-E Filter Magnetic Adiabatic Collimation and Electrostatic Filter: Magnetic guiding and collimation of e - Ø Transform E to E Electrostatic field for energy analysis Ø Sharp transmission depending on: Ø Emission angle Ø Radius in at B min Integrated energy resolution: ΔE = E B min B max

5 The KATRIN experiment 5 Previous MAC-E filter experiments: Troisk & Mainz Troisk experiment: Mainz experiment: Re-analysis 2011: 2 m ν e ) = ( 0.67 ± 1.89± ( 1.68) ev m( ν e ) < ev V.N. Aseev et al., Phys. Rev. D 84 (2011) Final result 2004: 2 m ν e ) = ( 0.6 ± 2.2 ± ( 2.1) ev m( ν e ) < 2. 3 ev 2 2 C. Kraus et al., Eur. Phys. J. C 40 (2005) 447

6 The KATRIN experiment 6 The KATRIN experiment The KArlsruhe TRItium Neutrino experiment: Next generation direct neutrino mass experiment at KIT International collaboration: ~120 members 15 Institutions in 5 countries: CZ, D, ES, RUS, US Member Institutions:

7 The KATRIN experiment 7 The KATRIN experiment KATRIN sensitivity: 3 full years of beam time: systematic and statistical error about equal: σ stat = ev 2 σ syst < ev 2 Sensitivity: m(ν) = 200 mev (90 % C.L.) = 350 mev (5 σ) KATRIN beyond m(ν): sterile neutrinos: light (ev-range) Ø reactor anomaly heavy (kev-range) Ø warm dark matter Technological advances: Precision high voltage Vacuum technology Field computation & particle tracking etc.

8 The KATRIN experiment 8 The KATRIN experiment ~70 m KATRIN sensitivity: 3 full years of beam time: systematic and statistical error about equal: σ stat = ev 2 σ syst < ev 2 Sensitivity: m(ν) = 200 mev (90 % C.L.) = 350 mev (5 σ) KATRIN beyond m(ν): sterile neutrinos: light (ev-range) Ø reactor anomaly heavy (kev-range) Ø warm dark matter Technological advances: Precision high voltage Vacuum technology Field computation & particle tracking etc.

9 The KATRIN experiment 9 The KATRIN experiment Windowless gaseous tritium source (WGTS) T 2 source with 1.7 x Bq 10 m long, 9 cm tube Free flowing T 2 gas Stable on 10-3 level in Inlet pressure Temperature Magnetic field Tritium fraction Largest source of systematics Delivery to KIT today tomorrow Rate stable on 10-3

10 The KATRIN experiment 10 The KATRIN experiment Differential pumping section (DPS) Tritium retention by 10 5 Active pumping with 4 TMPs 5 superconducting 5.6 T Magnets set-up at KIT SC magnet site acceptance test successful Beam line assembly ongoing

11 The KATRIN experiment 11 The KATRIN experiment Cryogenic pumping section (CPS) Tritium retention > 10 7 Cryo-pumping of residual gas Argon frost on K T Delivered to KIT on July 30, 2015 Setup and site acceptance test ongoing

12 The KATRIN experiment 12 The KATRIN experiment Spectrometer and detector section Tandem spectrometer setup Pre-Spectrometer Pre-filter e - /s 10 3 e - /s Used for R&D for Main Spec Main Spectrometer Main energy analysis ΔE = 0.93 ev Focal plane detector (FPD) 148 Pixel Si-PIN diode ΔE ~ 2 kev Everything on site and commissioned

13 The KATRIN experiment 13 Spectrometer and Detector commissioning Three phases: SDS-I 2013; SDS-II: 2014/15; SDS-IIb: Mid-2015 Subsystems: Main spectrometer Focal plane detector Angular selective e - -source Tests: Hardware, Software, Slow Control Transmission Properties Background

14 The KATRIN experiment Spectrometer and Detector commissioning Electron Optics Angular selective e--source: quasi mono-energetic photo-ecreated with UV-light on Au surface fast non-adiabatic acceleration of e in non-parallel E and B fields 4 axis movement: 2 axis to cover flux tube 2 axis to change pitch angle 14

15 The KATRIN experiment 15 Spectrometer and Detector commissioning Electron Optics Alignment: Whole wafer can be covered

16 The KATRIN experiment 16 Spectrometer and Detector commissioning Electron Optics Alignment: Whole wafer can be covered Characterization results: Angular selectivity shown Width: ΔE 1.2 ev E B min E = 18.6 kev; B min = 0.38 mt; B max = 5 T B max Preliminary

17 The KATRIN experiment 17 Spectrometer and Detector commissioning Electron Optics Alignment: Whole wafer can be covered Characterization results: Angular selectivity shown Width: ΔE 1.2 ev E B min E = 18.6 kev; B min = 0.38 mt; B max = 5 T B max Small changes over the wafer Detailed analysis ongoing Ø E+B-field distributions in analyzing plane Preliminary

18 The KATRIN experiment 18 Spectrometer and Detector commissioning Background: Stored particles Sources: Radioactive decays in volume Secondary processes 219 Rn emanating from NEG pumps

19 The KATRIN experiment 19 Spectrometer and Detector commissioning Background: Stored particles Sources: Radioactive decays in volume Secondary processes 219 Rn emanating from NEG pumps Identification: Elevated pressure (~10-8 mbar) High multiplicity events

20 The KATRIN experiment 20 Spectrometer and Detector commissioning Background: Stored particles Sources: Radioactive decays in volume Secondary processes 219 Rn emanating from NEG pumps Identification: Elevated pressure (~10-8 mbar) High multiplicity events Countermeasure: ln 2 cooled baffles in front of NEG pumps

21 The KATRIN experiment 21 Spectrometer and Detector commissioning Background: Stored particles Sources: Radioactive decays in volume Secondary processes 219 Rn emanating from NEG pumps Identification: Elevated pressure (~10-8 mbar) High multiplicity events Countermeasure: ln 2 cooled baffles in front of NEG pumps Results: Rn BG level negligible Preliminary

22 The KATRIN experiment 22 Spectrometer and Detector commissioning Background: secondary e - from vessel wall/inner electrode Sources: Cosmic rays Radioactive decays on surface Identification: Radial dependence of BG rate Specific test measurements Countermeasure: electric shielding with double layer inner electrode magnetic shielding

23 The KATRIN experiment 23 Spectrometer and Detector commissioning Background: secondary e - from vessel wall/inner electrode Sources: Cosmic rays Radioactive decays on surface Identification: Radial dependence of BG rate Specific test measurements Countermeasure: electric shielding with double layer inner electrode magnetic shielding Results: Shielding very effective Still remaining background Preliminary

24 The KATRIN experiment 24 Spectrometer and Detector commissioning Remaining Background: Non-baked: ~477±3 mcps Baked: ~312±3 mcps Design goal: 10 mcps Characteristics: flux tube volume dependent Not caused by: Cosmic muons External γ-rays Charged particles Working theory: Neutral particles entering flux tube e.g Hydrogen Rydberg atoms

25 The KATRIN experiment 25 Conclusions SDS Commissioning Test measurements on the spectrometer and detector section Hard- and software components operational w/o major problems Electron optics works as expected, detailed analysis ongoing Background further reduced, but still higher than design value Analysis and understanding of latest measurements ongoing Many more measurements Active background suppression Background model tests

26 The KATRIN experiment 26 Conclusions The KATRIN experiment Source and transport section tomorrow completely delivered to KIT Final assembly, site acceptance tests and commissioning ongoing Commissioning of whole system in 2016 First light (tritium) in mid/end 2016 Nominal intensity runs in 2017 Systematics investigations well on the way, mostly within budget

27 The KATRIN experiment 27 Thank you!