The CERN Antiproton Physics Programme The Antiproton Decelerator (AD) & ELENA

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1 The CERN Antiproton Physics Programme The Antiproton Decelerator (AD) & ELENA Dániel Barna Wigner Research Centre for Physics, Budapest, Hungary The CERN antiproton facilities Experiments, their programmes and results

2 The CERN Antiproton Decelerator Deceleration: 3.57 GeV/c 100 MeV/c (Ekin=5.3 MeV) Stochastic and electron cooling 1 bunch (~107 P) / 100 s (beam steering is painfully slow...)

3 ELENA The future of CERN ELENA = Extra Low ENergy Antiproton ring under construction! Extension to the Antiproton Decelerator, 30.4 m circumference Further decelerate antiprotons to 100 kev to improve efficiency of experiments Allow simultaneous running of multiple experiments

4 The ELENA Ring electron cooler

5 ELENA: electrostatic beamlines p/h- source for commissioning and quick beamline setup

6 ELENA: electrostatic beamlines p/h- source for commissioning and quick beamline setup pin pout

7 The ELENA Ion Switch Installed and commissioned with 100 kev H- beam

8 ELENA: electrostatic beamlines 4 bunches (1 μs) per shot: 4 experiments can run in parallel Quick electrostatic switches distribute beam to 4 experiments running parallel

9 ELENA: electrostatic beamlines Static spherical deflectors where no quick switching is needed

10 Quick switches and deflectors Fast deflector giving Fast deflector (<1(<1 μs)μs) giving mrad Borburgh et.al.) mrad kickkick (J. (J. Borburgh et.al.) Spherical electrostatic deflector giving 33o deflection

11 ELENA: electrostatic beamlines Straight sections: electrostatic quadrupoles - FODO transport

12 Quadrupole doublet + steerer unit

13 The antiproton physics programme at CERN

14 Running and planned experiments at the AD & ELENA ATRAP (Antihydrogen TRAP) H laser spectroscopy (to come), p magnetic moment & q/m ALPHA (Antihydrogen Laser PHysics Apparatus) H laser & mw spectroscopy, gravity (to come) Asacusa (Atomic Spectroscopy And Collisions Using Slow Antiprotons) H mw spectroscopy, p-he laser spectroscopy (mp/me), antiproton de/dx, σannihil in matter BASE (Baryon Antibaryon Symmetry Experiment) p magnetic moment & q/m AEGIS (Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy) H gravity GBAR (Gravitational Behaviour of Antihydrogen at Rest) Future, with ELENA: H gravity ACE (Antiproton Cell Experiment) cancer therapy, finished

15 Running and planned experiments at the AD & ELENA ATRAP (Antihydrogen TRAP) H laser spectroscopy (to come), p magnetic moment & q/m ts ALPHA (Antihydrogen Laser PHysics Apparatus) n e H laser & mw spectroscopy, gravity m i r Asacusa (Atomic Spectroscopy And Collisions Using Slow Antiprotons) e p H mw spectroscopy, x e p-he laser spectroscopy (mp/me), d e antiproton de/dx, σannihil in matter as b p BASE (Baryon Antibaryon Symmetry Experiment) a r p magnetic moment & q/m T AEGIS (Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy) H gravity GBAR (Gravitational Behaviour of Antihydrogen at Rest) Future, with ELENA: H gravity ACE (Antiproton Cell Experiment) cancer therapy, finished

16 The antiproton physics programme Most experiments want to compare protonantiproton properties: test CPT... which works very well so far. Need to find very tiny differences. High-precision physics. Antiproton physics is interesting: these experiments are the highlight visit targets when LHC is running it produces important physics results as well!

17 Antiproton physics is on the headlines t n e m i r e p x ALPHA e

18 Antiproton physics is on the headlines t n e m i r e p x e P A R T A

19 Antiproton physics is onathe headlines SACUSA ex ro d y h i t An! m a e gen b periment

20 Antiproton physics is onathe headlines SACUSA ex periment

21 Antiproton physics is onathe headlines SACUSA ex periment Assumin g contribut CPT, antiprotonic e to the o h fficial val elium results mass rat ue of pro io ton/elect ron

22 ACE Antiproton Cell Experiment

23 Antiproton Cell Experiment Goal: highest localised energy deposition in the tissues, without damaging the surroundings photons charged particles (protons) antiprotons Antiprotons can be more efficient Simulation

24 Antiproton Cell Experiment Until they stop, they deposit about the same energy as protons Annihilation: ~ 30 MeV strongly localised energy deposition π π π p p n n π n π π π ph ot on p p π Relativistic pions have small energy deposition Nucleus recoil: slow, low range Fission fragments slow, short range

25 Antiproton Cell Experiment Target: cells suspended in gel Sliced after irradiation to measure survival rate 50 MeV antiproton beam

26 Antiproton Cell Experiment Survival probability non-targeted zone: higher survival rate Protons Targeted zone: smaller survival rate Antiprotons Depth Depth

27 ALPHA Synthesis of antihydrogen Laser & MW spectroscopy, gravity e+ source Superconducting Penning trap

28 Production and trapping of antihydrogen for laser spectroscopy 1) Capturing antiprotons Penning-Malmberg trap (=multiring trap) Longitudinal m a p (5.3 MeV) gnetic field

29 Production and trapping of antihydrogen for laser spectroscopy 1) Capturing antiprotons 2) Cooling by electrons in the same trap

30 Production and trapping of antihydrogen for laser spectroscopy 3) To capture oppositely charged positrons in the same trap: modify the potential antiprotons positrons V1 V2 V3 V7

31 Production and trapping of antihydrogen for laser spectroscopy 4) Antihydrogen synthesis Antiprotons need to get in contact with positrons, at low velocities antiprotons Excite axial motion of antiprotons... positrons...in an anharmonic potential (frequency is a function of amplitude) Use a frequency-chirped excitation (frequency is function of time) to precisely control the oscillation amplitude......and align the 'turnover' point of antiprotons (v=0) with positrons Autoresonant excitation (C.Amole, et.al., Phys. Plasmas 20, (2013))

32 Production and trapping of antihydrogen for laser spectroscopy 5) Trap antihydrogen for laser spectroscopy The neutral antihydrogen escapes the Penning-Malmberg trap immediately. Add a multipole magnetic field H ( Ioffe-Pritchard trap) with minimal magnetic field at the centre. The low field seeking spin-states of H can be trapped if initial kinetic energy < trap depth (for more than 1000 s!) Nature 7 (2011), 558

33 Alpha achievements H synthesized and trapped routinely (1 trapped H per attempt (20min) & 104 p), practically arbitrarily long (Nature 7 (2011), 558) Shining on-resonance MW onto trapped H induced spin-flip and escape from trap (yes-no experiment, no spectroscopy yet) (Nature 483(2012), 439) Will be improved in future resonant MW on Quickly switch off magnetic trap and observe free fall (annihilation time [s] position) -65 < mh,grav / mh,inertial < 75 (95% conf.lev) Dedicated setup (vertical trap) is planned in the future 1s-2s laser spectroscopy is coming this summer, probably.

34 Spectroscopy of antihydrogen TODAY: ALPHA: ~ 1 trapped H per attempt (104 p ) ATRAP: ~ 5 trapped H per attempt (106 p, 2 heures) FUTURE (probably this year): laser spectroscopy of trapped antihydrogen

35 H 1s-2s laser spectroscopy with a single atom? Las er H has a finite oscillation in the trap Overlap with the focussed laser beam? Need long interaction time. Cosmic background would exceed the signal over a long period (remember: there is probably just 1 H in the trap) After a 1s --> 2s transition a second photon from the same laser ionizes the H Keep the charged-particle trap ON as well, which captures p after the ionization Integrate over a long time Then suddenly switch off the trap and detect if there was a p

36 ATRAP Antihydrogen synthesis and laser spectroscopy, p q/m and μ

37 Antihydrogen production by Cesium (ATRAP) Cs Cs (excited)

38 Antihydrogen production by Cesium (ATRAP) e+ ee+ e+ e- ee+ e- Cs+

39 Antihydrogen production by Cesium (ATRAP) p e+ e- H (excited) Possible to control H state by the laser

40 Magnetic moment of antiproton: ATRAP B~5.7 Tesla Penning trap -V +V p +V -V Oscillation in longitudinal electric potential

41 Magnetic moment of antiproton: ATRAP Penning trap + magnetic bottle -V +V +V -V

42 Magnetic moment of antiproton: ATRAP Penning trap + magnetic bottle -V +V p +V -V Slower oscillation

43 Magnetic moment of antiproton: ATRAP Penning trap + magnetic bottle -V +V p +V -V Faster oscillation Measure frequency to determine spinstate Induce spin flips via MW Determine spin-flip probability vs. MW frequency

44 Magnetic moment of antiproton: ATRAP Resonance Line shape due to p sampling the inhomogeneous B field of the trap J. DiSciacca, et.al., PRL 110(2013), p

45 Magnetic moment of antiproton: ATRAP p Precision: μp = μp (5 ppm) J. DiSciacca, et.al., PRL 110(2013),

46 BASE Baryon Antibaryon Symmetry Experiment antiproton & proton: q/m & μ

47 Antiproton charge-to-mass ratio Measure cyclotron frequencies of a p and a Halternatingly in the same trap (q/m)p (q/m)p = 1 ± BASE - S.Ulmer, et.al., Nature 524 (2015), 196

48 Magnetic moment of antiproton Double-trap: BASE Try to make spin-flip via MW excitation Magnetic bottle detect spin-state

49 Magnetic moment of antiproton Double-trap: BASE Try to make spin-flip via MW excitation Magnetic bottle detect spin-state Today: Δμ/μ = 3 x 10-9 with a single proton Repeat with a single antiproton! (A. Mooser, et.al.: Nature 509 (2014), 596)

50 Asacusa experiment Antihydrogen group

51 MW spectroscopy of H/H (Asacusa) RFQ decelerator (100 kev) Superconducting Penning trap capture and cooling Positron accumulator Positron source Synthesis trap

52 MW spectroscopy of H/H (Asacusa) MW cavity try to make a transition to a highfield-seeking state Synthesis trap. Its magnetic trap focuses the low-fieldseeking states of H

53 MW spectroscopy of H/H (Asacusa) Sextupole filter: focuses only if no transition occured Detector MW cavity try to make a transition to a highfield-seeking state Synthesis trap. Its magnetic trap focuses the low-fieldseeking states of H

54 frequency [GHz] rate at detector [Hz] MW spectroscopy of H/H (Asacusa) magnetic field [T] With hydrogen beam! ν-ν0 [khz] M.Diermaier,et.al., Hyperfine Interactions 233(2015), 35 TODAY: 80 H detected (without the MW cavity) Relative precision of 10-7 reached with a hydrogen beam FUTURE: MW spectroscopy of H (needs a lot of H!!)

55 Gravity experiments

56 AEGIS

57 Antimatter & gravity - AEgIS p e+ SiO2

58 Antimatter & gravity - AEgIS e+ ep Laser (excite the positronium) e+ SiO2

59 Antimatter & gravity - AEgIS e- H H Stark acceleration H H e+ SiO2 H emission in 4π

60 Antimatter & gravity - AEgIS Moiré deflectometer The periodic pattern is displaced due to gravity Detector: emulsion! (Gives best spatial resolution; no time resolution is needed)

61 GBAR Gravitational Behaviour of Antihydrogen at Rest

62 Antimatter & gravity: GBAR electron linac e+ production target

63 Antimatter & gravity: GBAR e+ production target e+ es) P ite c x e r( e s La

64 Antimatter & gravity: GBAR H+ trap H+ trapped together with Be+ Be+ cooled by laser H+ cooled by Be+ down to ~20 μk (~1 m/s) Ionisation by laser: H+ H (neutral, starts falling) Mesure the time-of-flight

65 Asacusa experiment antiprotonic helium spectroscopy group

66 Trapping antiprotons? All experiments so far used Penning traps (or variants of it) to trap antiprotons and make precise measurements on it, or create antihydrogen Is this the only way?

67 An alternative way to trap antiprotons exotic atoms P stops in material replaces an electron in an atomic orbit cascades down immediately (and annihilates) Emitted radiation: X-ray. Spectrum mp (precision: 5 x 10-5) Antiprotonic helium a unique exotic atom P replaces one electron: nucleus + P + electron in high Rydberg state (n~38, l~n-1) ~3% in metastable states (lifetime: 3-4 μs, enough for experimenting) antiproton's atomic transitions are in the visible range (laser spectroscopy, high precision) Simple enough for 10-9 calculations, or better (Master of it: V. Korobov) An exotic atom is a Nature-made trap, free from man-made imperfections # of annihilations [a.u.] 97% 3% metastable Time [μs]

68 Principle of laser spectroscopy of phe P principal quantum number P orbital quantum number

69 Principle of laser spectroscopy of phe Why metastable? In high-l states, negligible overlap with the nucleus Electron removes degeneracy, protects from collisions Due to large ionization potential: Auger decay would require transitions with large Dn, which would require large DL (suppressed) P orbital quantum number P principal quantum number

70 Principle of laser spectroscopy of phe Laser-induced population transfer

71 Principle of laser spectroscopy of phe H-like ion with degenerate levels Laser-induced population transfer

72 Principle of laser spectroscopy of phe p p p Collisions: Stark mixing Laser-induced population transfer

73 Principle of laser spectroscopy of phe p p p Collisions: Stark mixing Laser-induced population transfer TIME [ns]

74 What exactly can we learn from P-He spectroscopy? Measure atomic transition frequencies of antiprotonic helium: νexp Compare it to theoretical 3-body calculations: νth [V.I. Korobov, for example: Phys. Rev. A77 (2008) ] Interpretation: Frequency is function of many constants: νth(mhe, q, me, mp) Use this hydrogen-like parametrization: m * p ν n, l n ',l ' = R c Z eff (n, l, n ', l ' )( 2 2 ) me n n' Known to extremely high precision Let νth(mp/me) νexp Screening by electron; use QED to calculate mp/me a dimensionless constant

75 Long history, continuously increasing precision AD, no RFQ decelerator: high density target needed to stop p collisional shifts LEAR Pulse-amplified CW laser, frequency comb T=10K decelerating-rfq, pbar stops in lowdensity target laser linewidth 2-photon spectroscopy (overcome Doppler-limit) Better cryostat at 1.5 K

76 Experimental layout kev

77 Asacusa: laser spectroscopy of p-he Target: helium gas, T=1.5 K RFQ Decelerator (100 kev)

78 The Asacusa phe beamline & exp.

79 Measured resonance profiles with 2-photon spectroscopy P 4He (33,32) (31,30) P 3He (35,33) (33,31) -1 0 Laser frequency offset [GHz] Laser frequency offset [GHz] 1 Fractional precision of frequency: x P He (36,34) (34,32) Hyperfine lines caused by the interaction between Se lp (S3He) Precision of antiproton/electron mass ratio: 1.3 x 10-9 Agreement with proton within errorbars -1 0 [Nature 475 (2011) 484] Laser frequency offset [GHz] 1 CODATA is using these results for proton/electron mass ratio (assuming CPT)

80 (Anti)proton-electron mass ratio Indirect (spin-flip measurements) CODATA 2010 {

81 Summary CERN has an intensive antiproton programme Will continue for the coming years with ELENA (under construction) Low-energy, high-precision experiments Measuring fundamental constants, testing symmetries Antiproton physics is interesting, it has produced and is expected to produce headline news...