The AEgIS Experiment Measuring the Gravitational Interaction of - PowerPoint PPT Presentation

The AEgIS Experiment Measuring the Gravitational Interaction of Antimatter Andreas Knecht / CERN on behalf of the AEgIS collaboration LEAP 2013, 10/6/2013

AEgIS Collaboration University of Oslo and University CERN, Switzerland of Bergen, Norway INFN Genova, Italy Czech Technical University, INFN Bologna, Italy Prague, Czech Republic Kirchhoff Institute of Physics, INFN Padova-Trento, Italy Heidelberg, Germany Max-Planck-Insitut für ETH Zurich, Switzerland Kernphysik Heidelberg, Germany INFN, Università degli Studi and Laboratoire Aimé Cotton, Politecnico Milano, Italy Orsay, France University College, London, INFN Pavia-Brescia, Italy United Kingdom Stefan Meyer Institut, INR Moscow, Russia Vienna, Austria Université Claude Bernard, University of Bern, Switzerland Lyon, France Andreas Knecht LEAP 2013, 10/6/2013 2

Motivation First direct test of the Weak Equivalence Principle involving antimatter Direct tests so far only for matter systems Validity for antimatter inferred from heavily debated indirect arguments Theory could accommodate differences (e. g. through potential including gravivector and graviscalar) Nieto and Goldman, Phys. Rep. 205, 221 (1991) Amole et al., Nat. Comm. 4:1785 (2013) Andreas Knecht LEAP 2013, 10/6/2013 3

Motivation And quite generally: Experimental test of the gravitational interaction in a new sector - one for the textbooks (and for the public)! Andreas Knecht LEAP 2013, 10/6/2013 4

AEgIS Experimental Goal Primary goal: Measurement of gravitational acceleration g for antihydrogen with 1% accuracy Secondary goals: Spectroscopy of antihydrogen Study of Rydberg atoms Positronium physics: formation, excitation, spectroscopy Andreas Knecht LEAP 2013, 10/6/2013 5

AEgIS Experimental Strategy Produce ultra cold antiprotons Form positronium by interaction of positrons with a porous target (pulsed) Laser excite Ps to get Rydberg Ps (pulsed) ∗ + e − Ps ∗ + p → H Form Rydberg cold antihydrogen (pulsed) by Stark accelerate the antihydrogen with inhomogeneous electric fields → Pulsed production of a cold beam of antihydrogen Measure the gravitational acceleration in a classical moiré deflectometer Storry et al., PRL 93 , 263401 (2004) Vliegen and Merkt, J. Phys. B: At. Mol. Opt. Phys. 39 , L241 (2006) Andreas Knecht LEAP 2013, 10/6/2013 6

Antihydrogen Formation ∗ + e − Ps ∗ + p → H positronium converter e + Ps 0.09 Ps n Ps = 35 0.08 laser excitation Ps* 0.07 Ps* 0.06 H beam H* H* 0.05 prob 0.04 antiproton accelerating trap electric field 0.03 H* 0.02 Positronium charge exchange technique: 0.01 Large cross-section, scales as n 4 Narrow and defined final state distribution 0 0 10 20 30 40 50 60 70 80 Antihydrogen production from antiprotons at rest n(H) Andreas Knecht LEAP 2013, 10/6/2013 7

Moiré Deflectometer position-sensitive detector grating 1 grating 2 gt ² L L atomic beam Classical deflectometer (shadow mask) Third grating replaced by position-sensitive Gr Gr units units detector Andreas Knecht LEAP 2013, 10/6/2013 8

Moiré Deflectometer Phase (rad) 3 2.5 2 1.5 1 0.5 0 0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016 0.0018 0.002 0.0022 time (s) Phase shift as a function of time (velocity of antihydrogen) gives gravitational acceleration: Δ z ~ gt 2 Andreas Knecht LEAP 2013, 10/6/2013 9

Experimental Apparatus 5T magnet 1T magnet Positron accumulator _ p from AD Andreas Knecht LEAP 2013, 10/6/2013 10

Location Layout of the zone Andreas Knecht LEAP 2013, 10/6/2013 11

Experimental Installation Zone early 2011 Zone late 2012 Andreas Knecht LEAP 2013, 10/6/2013 12

5T Catching Traps HV 1 HV 2 HV 3 Andreas Knecht LEAP 2013, 10/6/2013 13

1T Formation Traps Andreas Knecht LEAP 2013, 10/6/2013 14

Central Antihydrogen Detector Scintillating fibre detector operating at 4K 800 channels readout by SiPM 200 MHz readout detecting hit pattern Andreas Knecht LEAP 2013, 10/6/2013 15

Positron System 800 MBq 22 Na source Solid neon moderator Positron trap Positron accumulator Buffer gas cooling Pulsed transfer line ~0.1T Andreas Knecht LEAP 2013, 10/6/2013 16

Positron System e + M o d e r a t i o n - Tr a n s p o r t Time (s) efficiency ~ 2.5 10 -2 Dump intensity 7-8 10 6 Spot dimension 4-5 mm Lifetime ~30 s 0 20 40 60 80 100 120 Transport efficiency Fill time ~120 s Trapping-dumping efficiency ~ 0.14 6 e + 7-8 10 Lifetime = 29+/-2 s ~80-90 % Dump intensity 7-8 10 6 e + fill time = 120 s Spot dimension 1-2 mm 6 e + 6 10 Lifetime = 25+/-2 s fill time = 100 s counts (a.u.) 6 e + 5 10 Lifetime = 12+/-1 s Ongoing work to increase rates 6 e + 3 10 fill time = 38 s and efficiencies 0 200 400 600 800 Pulse number 5-6 x 10 4 e + from trap e+ Andreas Knecht LEAP 2013, 10/6/2013 17

Commissioning Results Antiproton catching vs applied high voltage Cold and hot antiproton fractions vs. electron cooling time 1 1.4 0.9 1.2 0.8 Cold / hot antiproton fraction ] 5 Antiprotons caught [ x10 0.7 1 0.6 0.8 0.5 0.6 0.4 0.3 0.4 0.2 0.2 0.1 0 0 1 2 3 4 5 6 7 8 9 0 5 10 15 20 25 30 35 40 Trapping voltage [kV] Antiproton cooling time [s] Trapping, cooling Andreas Knecht LEAP 2013, 10/6/2013 18

Commissioning Results 3 10 × Trapped antiprotons 140 120 100 Hot antiprotons storage time 9 KV 80 60 40 20 0 0 50 100 150 200 250 300 sec Lifetime ~500 s Cold antiproton storage Storing Andreas Knecht LEAP 2013, 10/6/2013 19

Commissioning Results Manipulations Andreas Knecht LEAP 2013, 10/6/2013 20

Commissioning Results Extraction pulse from accumulator Scintillator pulses from positron annihilation in 1T Positron transfers through transfer line and 5T into 1T magnet Andreas Knecht LEAP 2013, 10/6/2013 21

Detector Tests See poster by O. Karamyshev Parasitic tests: Explore different candidate technologies for the (downstream) antihydrogen detector Silicon detectors (strip, pixel) MCP Emulsions Andreas Knecht LEAP 2013, 10/6/2013 22

Silicon Detectors _ p 3D pixel sensor designed for the ATLAS upgrade Also tested: strip sensor, Mimotera Andreas Knecht LEAP 2013, 10/6/2013 23

Mimotera Detector Probability FTF 7000 Y 0.14 Chips 100 Data 0.12 6000 0.1 80 5000 0.08 0.06 4000 60 0.04 3000 0.02 40 Preliminary 2000 0 2 DATA 20 1000 /N 1 SIM 0 0 N 0 0 20 40 60 80 100 0 5 10 15 20 25 30 X E [MeV] tot 112 x 112 silicon pixel detector, 153 μ m x 153 μ m, 15 μ m active depth Detailed comparison of data vs simulation Test of Monte Carlo treatment of antiproton annihilations on bare silicon Publication forthcoming! Andreas Knecht LEAP 2013, 10/6/2013 24

Emulsions Exposure of emulsion an#proton( Development in Focus& dark room Emulsion) Scanning on layer)) (50)micron)) automated microscopes Glass%base% Base (glass or plastic) (several 100 μ m) 1%mm% Offline track and vertex finding algorithms 1 μ m vertex resolution See talk by J. Storey Friday @ 9:55 am Andreas Knecht LEAP 2013, 10/6/2013 25

First Test of Moiré Deflectometer ~100 keV antiprotons 7 hour exposure Bare emulsion behind deflectometer d emulsion ref Andreas Knecht LEAP 2013, 10/6/2013 26

First Test of Moiré Deflectometer Cross-correlation method Period 100 Preliminary 40.8 Antiproton fringes observed 40.6 80 40.4 40.2 Alignment of gratings using 60 40 light and single grating 39.8 40 39.6 Promising results! 39.4 20 39.2 39 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 Rotation (rad) Publication forthcoming! Andreas Knecht LEAP 2013, 10/6/2013 27

Conclusions and Outlook Installation of apparatus largely completed and commissioned Parasitic measurements essential in converging to an optimal deflectometer/detector layout Next steps: Install proton source, hydrogen detector Commission Rydberg positronium formation Work on hydrogen formation/characterization Goal: Be ready for antihydrogen beam formation in summer 2014! Andreas Knecht LEAP 2013, 10/6/2013 28

Backup Andreas Knecht LEAP 2013, 10/6/2013 29

Positronium target - parameters

Ultracold antiprotons Antiprotons in the trap cannot be directly cooled to 100 mK Cool antiprotons by collisions with a partner particle stored in the same trap that can be cooled electrons Resistive cooling with a resonant tuned Negative ions: La - circuit + radiation cooling Laser cooling of La _ e- antiproton Ultimate temperature: 240 nK L C antiprotons Embedded electron cooling, adiabatic cooling, evaporative cooling, ...  A demonstration of laser cooling of negative ions is needed  Experiment in progress at MPI (members of AEGIS)