Transmission measurements at the KATRIN main spectrometer

Transcription

1 Transmission measurements at the KATRIN main spectrometer Stefan Groh GK-Workshop Bad Liebenzell, October 2013 Institute for Experimental nuclear Physics (IEKP) KIT University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association

2 Outline How does KATRIN work Commissioning of spectrometer and detector Alignment of egun and Detector Transmission function measurement Radial potential scan Transmission function at high rate 2

3 Outline How does KATRIN work Commissioning of spectrometer and detector Alignment of egun and Detector Transmission function measurement Radial potential scan Transmission function at high rate Model independent measurement of the neutrino mass with a sensitivity of 200 mev ( 90% C.L.) 3

4 Tritium beta decay Neutrino mass takes away energy that changes shape of electron spectrum Precise spectroscopy of beta decay electrons necessary 4

5 potential in kv Experimental Setup source transport spectrometers + detector How to measure the energy of the electrons?

6 Why the big spectrometer? Source: isotropic e - emission Cyclotron motion along field line Fixed polar angle between p and B Electric field only filters long. comp. E E kin = E + E Problem: How to filter the electrons according to their kinetic energy? µ is conserved in an adiabatic motion µ = E B Solution: Decrease the polar angle of the electrons at the analyzing point reduce magnetic field at the analyzing point E E 6

7 The MAC-E-Filter principle 7

8 trans. prob. The energy resolution e e ϴ = 0 e ϴ = 60 1 ret. potential: V electron energy: ev E start q U 0 8

9 trans. prob. The energy resolution e e ϴ = 0 e ϴ = 60 1 ret. potential: V electron energy: ev E start q U 0 9

10 trans. prob. The energy resolution e e ϴ = 0 e ϴ = 60 1 ret. potential: V electron energy: ev E start q U 0 10

11 The transmission function 11

12 Integral spectrum E 0 N qu dn E de 0, mv 2 T E, qu de 0 Integral spectrum is convolution of differential spectrum with transmission function 12

13 Integral spectrum Precise knowledge and detailed understanding of the transmission function is essential for a successful neutrino mass measurement 13

14 Outline How does KATRIN work Commissioning of spectrometer and detector Alignment of egun and Detector Transmission function measurement Radial potential scan Transmission function at high rate Measurement phase finished last week 14

15 Commissioning of Spectrometer and Detector Main Spectrometer angular selective E-Gun Detector Section Main goals: Test of Hardware and Slowcontrol components Measurement and Understanding of background Understanding of transmission properties Verification of simulations software and models 15

16 Focal plane detector system Si-PIN Diode with 148 Pixel See talk by J. Schwarz, later today 16

17 Electron Gun Electron Gun: Quasi monoenergetic Pulsed for ToF measurements Movable to cover full detector flux 17

18 Outline How does KATRIN work Commissioning of spectrometer and detector Alignment of egun and Detector Transmission function measurement Radial potential scan Transmission function at high rate 18

19 Flux tube - egun 19

20 Flux tube main spectrometer egun detector 20

21 Flux tube - detector Detailed understanding of field lines is very important 21

22 egun-detector alignment Misalignment of egun and detector needs to be taken into account in the analysis 22

23 Different magnetic coil setup 23

24 Different magnetic coil setup 24

25 Comparison with simulation Measurement Simulation 25

26 Comparison with simulation Field lines for different settings can be very good reproduced by simulations plots by N. Stallkamp 26

27 Outline How does KATRIN work Commissioning of spectrometer and detector Alignment of egun and Detector Transmission function measurement Radial potential scan Transmission function at high rate 27

28 Transmission function Spectrometer works as MAC-E-Filter commissioning successful 28

29 Outline How does KATRIN work Commissioning of spectrometer and detector Alignment of egun and Detector Transmission function measurement Radial potential scan Transmission function at high rate 29

30 Measure TF at different radii 30

31 Radial transmission scan 31

32 Radial transmission scan 32

33 Radial transmission scan 33

34 Radial transmission scan 34

35 Radial potential measurement Preliminary 35

36 Outline How does KATRIN work Commissioning of spectrometer and detector Alignment of egun and Detector Transmission function measurement Radial potential scan Transmission function at high rate 36

37 Detector efficiency at high rates Efficiency of detector depends on rate and time profile 37

38 Transit flight times at different transmission points monte carlo Δt 40 µs 38

39 Transit flight times at different transmission points monte carlo Δt 20 µs 39

40 Transit flight times at different transmission points monte carlo Δt 5 µs 40

41 Influence on transmission function monte carlo Transmission functions can only be measured at low rate (<5 kcps) 41

42 TF Measurement at high rate Predicted high rate effect could also be measured Upgrade of the detector electronics is already planned 42

43 Conclusion KATRIN uses the MAC-E-Filter technique to measure an integrated electron spectrum Detailed knowledge of transmission function is important for neutrino mass analysis Successful commissioning of the spectrometer and detector section Electron gun can be used for transmission function measurements and potential mapping Predicted high rate -effects of the transmission function could be confirmed by measurements 43

44 Open questions? zzzzzz What tool does he use to track particles in that low energy regime? What's for lunch today? 44

45 BACKUP SLIDES 45

46 Kassiopeia KATRINs main particle tracking framework Modern C++ design Field solvers for electric and magnetic fields Particle generators Multiple tracking routines Multiple Interaction routines Visualization Easy configurable via xml files Interface to measurement parameters Full modular Also used by other experiments 46

47 KEMField Standard Field Solver for Kassiopeia (E and B) Very detailed model of the main spectrometer > 4 Million Elements Employs MPI and OpenCL T.J. Corona 47

48 Main spectrometer 48

49 Detector 49

50 Detector 50

51 MORE BACKUP SLIDES 51

52 Lunch? Chicken with pepper and rice and red fruit jelly for desert 52