The GBAR experiment. Dirk van der Werf

Transcription

1 The GBAR experiment Dirk van der Werf

2 principle detector Laser (t 0 ) gravity J.Walz & T. Hänsch" General Relativity and Gravitation, 36 (2004) 561 detector (t 1 ) 2

3 principle detector Laser (t 0 ) gravity J.Walz & T. Hänsch" General Relativity and Gravitation, 36 (2004) 561 detector (t 1 ) 2

4 principle detector Laser (t 0 ) gravity J.Walz & T. Hänsch" General Relativity and Gravitation, 36 (2004) 561 detector (t 1 ) Velocity fluctuation Temperature equivalent 100 m/s 3 m/s 0.1 m/s 1 K 1 mk 1 µk Desired range" 2

5 How? Produce via two reactions: 3

6 How? Produce via two reactions: Trap it in a Paul trap and sympathetically cool the anti-ion with Be + 3

7 How? Produce via two reactions: Trap it in a Paul trap and sympathetically cool the anti-ion with Be + " Detach the second positron with a laser pulse and let the fall 3

8 Schematic 4

9 GBAR Layout D P van der Werf The GBAR experiment Bern 14 November

10 Drift tube 100#keV#p#pulse# 300#ns#(1.3#m)# dri9#tube# 1#keV#(0.2#m)# 4π#mm#mrad# 40π#mm#mrad# 5#99#kV# switch# 5#1#kV# 6

11 Multi-Reflection Time-of-Flight separator" (Electrostatic Ion Beam Trap) R. N. Wolf et al. IJMS (2013) 7

12 Deceleration and pulsed drift tube/mirror: " another concept From%ELENA:% 100%keV%p%pulse% 300%ns%(1.3%m)% 4π%mm%mrad% 1%keV% 0.2%m% 40π%mm%mrad% resistive (stochastic?) cooling! 1<keV% p%pulse% focusing optics <%99%kV% <%99%kV% 8

13 Schematic 9

14 Test experiment at Saclay Pulse stretcher Materials science line Beam switch RIKEN 5T MRT D P van der Werf The GBAR experiment Linac Bern 14 November

15 Production of moderated positrons Linac 4.3 MeV e Hz,~2.5 µs ~140 ma (peak) Water cooled W electron target ~1 MeV e+ B ~8 mt ~10 ev e+ Moderator: Annealed W mesh (~10 µm) Present slow e + rate s -1 Extrap. to 10 MeV linac s -1 target value s -1 " Present work on a new linac for Cern installation: 18 MeV, 300 Hz, 2 µs, 200 ma peak" New W moderator designed; Ne moderator to be studied 11

16 Positron trapping - MRT 12

17 Interaction area " " " " Positrons are converted into positronium Part of the Ps atoms will be excited (see later), i. e. laser radiation needs to be introduced Antiprotons will shoot through the positronium cloud to form Mesoporous film Substrate (Si) Ps Positron beam ~3 kev 13

18 Interaction area " " " " Positrons are converted into positronium Part of the Ps atoms will be excited (see later), i. e. laser radiation needs to be introduced Antiprotons will shoot through the positronium cloud to form Mesoporous film Substrate (Si) Ps Positron beam ~3 kev 13

19 Overall formation cross sections " For a pulse of 3 x 10 6 antiprotons: 1.2 for 1 kev + Ps(3d) " 3 for 2 kev + Ps(2p)" 0.9 for 6 kev + Ps(1s) 14

20 Status of 410 nm laser Ps excitation to 3d level : two photon excitation with 410 nm laser" Presently assembled at LKB" Will be installed at Saclay end 2013" Studying a laser for 2p excitation 15

21 Schematic 16

22 Cooling challenge 17

23 Catching & precision traps Capture trap Precision trap See talk of Hilico this afternoon 18

24 Photo detachment 19

25 Detection Scintillator counters Laser beams Scintillator counters z (cm) 0-10 Scintillator counters Cylindrical TPC top TPC Capture electrodes Paul trap * antihydrogen cloud top TPC Mirror Annihilation plate (movable) Cylindrical TPC Scintillator counters -20 bottom TPC Detection requirement:" TOF precision : 150 µs" Annihilation vertex precision : 1 mm" Background rejection through event topology" " Scheme under design: TPC with micromegas chamber (as in T2K near detector)" -30 Scintillator counters x (cm) 20

26 Quantum Reflection See talks of Dufour and Voronin this afternoon 21

27 GBAR timeline 22

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