Observation of the 1S-2S Transition in Antihydrogen

Transcription

1 Observation of the 1S-2S Transition in Antihydrogen Dirk van der Werf Swansea University CEA-Saclay ALPHA

2 What do we want to do Check CPT conservation Baryon asymmetry Standard model extension (SME): Assume some violation, i.e. Lorentz symmetry is broken in a particular way, then in a number of cases there will be a difference between the some of the properties between matter and antimatter (see e.g. V.A. Kostelecký and S. Samuel, Phys. Rev. D 39 (1989) 683) D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

3 Borrowed from Stefan Ulmer D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

4 Goals CPT theorem -> particles and antiparticles must have equal energy levels of bound states Compare the spectra of H and, testing CPT. Records for Hydrogen - 1S-2S transition known to 4.2 parts in C.G. Parthey et al. Phys. Rev. Lett. 107, (2011) - Ground state hyperfine transition known to 1.4 parts in H. Hellwig et al. Instrumentation and Measurement, IEEE Transactions 19, 200 (1970). D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

5 Penning Trap Trap for charged particles D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

6 Breit-Rabi Diagram To measure accurately electronic transition a trap for neutral atoms is necessary: use the spin state of the antihydrogen atom 20 trappable 'low-field seeking' states relative energy in frequency units [GHz] c = d = untrappable 'high-field seeking' states d c b a f bc f ad spin flip frequencies -20 a = b = Magnetic Field [T] D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

7 Magnetic trap Quadrupole Sextapole Octupole Decapole B/B w = B/B w r/r w D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

8 Magnetic field measurements Cyclotron excitation Heat non-neutral electron plasma Change quadrupole mode frequency f2 Typical measurement D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

9 ALPHA h SiliconEvent.VF48Timestamp:SiliconEve Installed: ~150k p/shot, >10h lifetime h Entries 209 Mean RMS SiliconEvent.VF48Timestamp hxy SiliconEvent.NTracks {Sil 5 4 hxy 4 Entries 209 Mean x Mean y RMS x RMS y catch and accumulation formation, trap and spectroscopy D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

10 D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

11 Laser Paths D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

12 D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

13 Cosmic D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

14 Two track D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

15 Three Track D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

16 Schematic Overview D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

17 Laser Setup The long-term average laser frequency at 972 nm is determined to a relative accuracy of D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

18 Experiment Procedure: 1. Make and Trap antihydrogen 2. Pulsing axial electric fields to remove antiprotons 3. Holding the trapped anti-atoms for 600 s 4. ramping down the trapping fields Three types of trials 1. On resonance : d d transition and then the c c transition are driven for 300 s each. 2. Off resonance : same as above, but the laser is detuned 200 khz down 3. No laser : no laser radiation is present during the 600-s hold time. During hold times, electrostatic blocking potentials so that anti- protons can only radially escape. fc c = 2,466,061,707,104(2) khz fd d = 2,466,061,103,064(2) khz 11 sets, change of measurement order between sets. D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

19 Simulation for 1 W laser power D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

20 Result 1 The MVA used for the 1.5-s shutdown window yields a cosmic ray background rate of ± s 1 Reconstruction efficiency: ± D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

21 Result 2 The MVA used for the 1.5-s shutdown window yields a cosmic ray background rate of ± s 1 Reconstruction efficiency: ± D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

22 Time evolution of the dataset. D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

23 Conclusion + Outlook The difference between the on- and off-resonance totals of 52 ± 10 (C-test19, one-sided P value of ). Our result is consistent with CPT invariance at a relative precision of about ,assuming the same line shape as for hydrogen Sensitivity ~ GeV Next year full line shape measurement D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

24 Funding D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February

25 ALPHA D E N M A R K NRCN Nuclear Research Center Negev Universidade Federal do Rio de Janeiro BRASIL TRIUMF D P van der Werf Observation of the 1S-2S Transition in Antihydrogen Seoul, 9 February