Hyperfine splitting in µp and µ 3 He +

Transcription

1 ==================================== Hyperfine splitting in µp and µ 3 He + µ CREMA collaboration A. Antognini PSAS 2016, Jerusalem p. 1

2 Hyperfine splitting in µp and µ 3 He + CREMA collaboration µ Measure E(2S 2P ) charge radii Measure E(HFS) magnetic radii - Muonic hydrogen (µp) -Muonicdeuterium(µD) -Muonichelium(µ He + ) - Hyperfine splitting in µ 3 He + - Hyperfine splitting in µp A. Antognini PSAS 2016, Jerusalem p. 1

3 Proton and deuteron puzzles? µd + iso µp dispersion 2012 dispersion 2007 CODATA-2010 H spectroscopy e-p, JLab e-p, Mainz Proton charge radius r p Talk: J. Kraut [fm] µd µp + iso CODATA-2010 D spectroscopy e-d scatt Deuteron charge radius r [fm] d A. Antognini PSAS 2016, Jerusalem p. 2

4 Charge and magnetic radii from scattering Extraction of R E from scattering is difficult Extraction of R M from scattering is more difficult R 2 E/M = 6dG E/M (Q 2 ) dq 2 Q2 =0 G E (Q 2 ) = 1 Q2 6 r2 p + Q4 120 r4 p LowQ 2 yields slope but sensitivity is small - Need larger lever-arm to get slope -LargerQ 2 more sensitive but higher-order terms - Need to have physical model or constraints - Need to have fit function with enough flexibility but not to much Talk: Lee and Kohl A. Antognini PSAS 2016, Jerusalem p. 3

5 Hyperfine splitting vs. 2S-2P spectroscopy The 2S-2P energy splitting (Lamb shift) E th L = (15) (10)R2 E (20) mev E finite size = 2πZα φ(0) 2 R 2 3 E R E = 6 G E (0) dg E dq 2 Q 2 =0 R 2 E d rρ E ( r)r 2 TPE: Two photon exchange The hyperfine splitting E 0 HFS (Zα) µ µ µ N φ(0) 2 E th HFS = (1) 1.301R Z (21) mev E finite size = 2(Zα)m r E 0 HFS R Z R Z = 4 π 0 dq Q 2 (G E (Q 2 ) G M (Q 2 ) 1) 1+κ p TPE: Two-photon-Exchange R Z = d 3 r r d 3 r ρ E ( r r )ρ M ( r ) A. Antognini PSAS 2016, Jerusalem p. 4

6 Objectives and impact Measure the 1S HFS in µ p and µ He with 1 ppm accuracy TPE contributions with 1 x 10 4 relative accuracy Polarizability with 10% relative accuracy Polarizability from theory Zemach radii 3 1 x 10 relative accuracy Zemach radii from scattering or H Magnetic radii A. Antognini PSAS 2016, Jerusalem p. 5

7 Objectives and impact Measure the 1S HFS in µ p and µ He with 1 ppm accuracy TPE contributions with 1 x 10 4 relative accuracy Polarizability with 10% relative accuracy Polarizability from theory Zemach radii 3 1 x 10 relative accuracy Zemach radii from scattering or H Magnetic radii A. Antognini PSAS 2016, Jerusalem p. 5

8 Objectives and impact Measure the 1S HFS in µ p and µ He with 1 ppm accuracy TPE contributions with 1 x 10 4 relative accuracy Polarizability with 10% relative accuracy Polarizability from theory Zemach radii 3 1 x 10 relative accuracy Zemach radii from scattering or H Magnetic radii - Precision experiments: hold the potential for surprises - Radii: benchmarks for lattice QCD and few-nucleon th. compare with scattering and H/He spectroscopy solve discrepancy between proton R M -Polarizabiliztycontributions compare to ChPT, dispersion+data, few-nucleon th. - TPE contributions compare to dispersion+data, few-nucleon th. A. Antognini PSAS 2016, Jerusalem p. 5

9 Two ways to the polarizability contribution ChPT Phenomenological: dispersion relations + g 1 (x, Q 2 ), g 2 (x, Q 2 ) + sum rules 2S-2P: Agreement HFS: First preliminary ChPT results A. Antognini PSAS 2016, Jerusalem p. 6

10 Two ways to the polarizability contribution ChPT Phenomenological: dispersion relations + g 1 (x, Q 2 ), g 2 (x, Q 2 ) + sum rules talk Carlson 2S-2P: Agreement HFS: First preliminary ChPT results A. Antognini PSAS 2016, Jerusalem p. 6

11 HFS theory status E HFS (1S) =[1 + QED + weak+hvp + Zemach + recoil + pol TPE Phys. Rev. A , Phys. Rev. A 83, , Phys. Rev. A 71, ] EHFS 0 µp µ 3 He + Magnitude Uncertainty Magnitude Uncertainty E HFS mev mev QED weak+hvp Zemach recoil pol ( ) ( ) G E (Q 2 ), G M (Q 2 ) G E, G M, F 1, F 2 g 1 (x, Q 2 ), g 2 (x, Q 2 ) A. Antognini PSAS 2016, Jerusalem p. 7

12 HFS theory status E HFS (1S) = [1 + QED + weak+hvp + Zemach + recoil + pol TPE Phys. Rev. A , Phys. Rev. A 83, , Phys. Rev. A 71, ] EHFS 0 µp µ 3 He + Magnitude Uncertainty Magnitude Uncertainty E HFS mev mev QED weak+hvp Zemach recoil pol ( ) ( ) G E (Q 2 ), G M (Q 2 ) G E, G M, F 1, F 2 g 1 (x, Q 2 ), g 2 (x, Q 2 ) pol (2S) arxiv arxiv δ E pol = 15 µev but ChPT groups have been triggered Ongoing measuremnts of g 2 at JLab A. Antognini PSAS 2016, Jerusalem p. 7

13 HFS theory status E HFS (1S) = [1 + QED + weak+hvp + Zemach + recoil + pol TPE Phys. Rev. A , Phys. Rev. A 83, , Phys. Rev. A 71, ] EHFS 0 µp µ 3 He + Magnitude Uncertainty Magnitude Uncertainty E HFS mev mev QED weak+hvp Zemach recoil pol ( ) ( ) G E (Q 2 ), G M (Q 2 ) G E, G M, F 1, F 2 g 1 (x, Q 2 ), g 2 (x, Q 2 ) pol (2S) E pol E Zemach Not yet computed but δ E pol E pol = 5% for the 2S-2P < 10% from prel. 2S-2P analysis arxiv arxiv δ E pol = 15 µev but ChPT groups have been triggered Ongoing measuremnts of g 2 at JLab A. Antognini PSAS 2016, Jerusalem p. 7

14 Magnetic radius from the hyperfine splitting Extraction of R M from R Z requires models for the form factors Model-independent determinations: RE 2 + R2 M = 1.35(12) fm2 (H) RE 2 + R2 M = 1.49(18) fm2 (µp) Karshenboim, arxiv: A. Antognini PSAS 2016, Jerusalem p. 8

15 Principle of the HFS experiments µ stops in gas and forms a muonic atom Alaserpulsedrivesthehyperfinetransition Need a method to detect the occurred transition Plot number of detected transitions versus the laser frequency see also talk A. Vacchi A. Antognini PSAS 2016, Jerusalem p. 9

16 Principle of the µp HFS experiment µ of 10 MeV/c are detected trigger the laser µ stops in H 2 gas (500 mbar, 50 K) µp(f=0) formation Laser pulse: µp(f=0) µp(f=1) σ + F=1 Collision: µp(f=1)+ H 2 H 2 +µp(f=0) + E kin Diffusion: the faster µp reach the target walls m= 1 m=0 m=+1 F=0 At the wall: µ transfer to high-z atom (µz) formation (µz) de-excitation MeV X-rays, e and µ capture Resonance: Number of X-rays/e /capture signals after laser excitation versus laser frequency µ Signal events: Laser excited µp reach wall in t [t laser,t laser + t] Cavity H gas 2 µp Cavity Background events: Thermalized µp reach wall in t [t laser,t laser + t] Scintillator Cool target to 50 K A. Antognini PSAS 2016, Jerusalem p. 10

17 Cross sections: thermalized vs. laser excited [Adamczak, 2015] Diffusion radius of µp in H 2 gas vt R σ trans N [Adamczak, EPJD 41, 493 (2007)] A. Antognini PSAS 2016, Jerusalem p. 11

18 Efficiencies and event rates Signal Background #1 Muon beam at 10 MeV/c with 5 mm diameter 600 /s 600 /s #2 Anti-coincidence rejection #3 Laser and DAQ trigger rate 240 /s 240 /s #4 Stops in gas (after anti-rejection) #5 Overlap laser volume/µ stop volume #6 µp density decrease due to diffusion #7 µ decay prior to laser time #8 Laser excitation probability (E = 0.6 mj, N = 400) #9 Fraction of µp with kinetic energy > 0.1 ev #10 µp reaching the walls (diffusion + decay...) #11 Detection efficiency for cascade/capture events #12 Multiplication of efficiencies #13 Event rate per hour on resonance #14 Time needed to see a 4σ effect over BG 5.5 h #15 Time needed for wavelength change 1 h #16 Number of points to be measured 170 #17 Beam time duration (70% up-time + setting up) 12 weeks πe5 anti-coincidence laser: short delay laser: large energy cryogenic cavity ±3σ theory uncertainty A. Antognini PSAS 2016, Jerusalem p. 12

19 Principle of the µ 3 He + HFS experiment µ of 10 MeV/c are detected trigger a laser µ stop in 3 He gas (50 mbar, 300 K) µ 3 He + F=0 25% Laser pulse: drives F=0 F=1 and F=1 F=0 transitions σ σ change of the avg. muon polarization Detect electron from muon decay F=1 m= 1 25% + m=0 m=+1 25% 25% Decay asymmetry: N e (left) increaese, N e (right) decreaese Resonance: N e (left) N e (right) vs. laser frequency A. Antognini PSAS 2016, Jerusalem p. 13

20 µ 3 He + resonance search (µhe) + + He + He He(µHe) + + He for precision experiment: p = 50 mbar (τ µ He + = 1.8 µs) for resonance search: p = few bar (all muons in molecular state) How much the muonic transition is disturbed by the molecule? Shift? Upper limit from µhe-e: 6 ppm [Pachucki and Karr PC] Splitting? Upper limit from µhe-e: 4 GHz / 323 THz = 13 ppm Number of frequency points: 650 Time needed for a 4σ effect over BG 2 h Weeks needed for resonance search (scan) 12 (2) A. Antognini PSAS 2016, Jerusalem p. 14

21 Laser requirements Experiment µp 2S-2P (2009) µp HFS µ He + 2S-2P (2014) µ 3 He + HFS Wavelength 6.0 µm 6.7 µm nm 930 nm Pulse energy 0.15 mj 1.5 mj 12-6 mj 50 mj Avg. Rate 220 Hz 250 Hz 220 Hz 500 Hz Bandwidth 300 MHz 300 MHz < 300 MHz 500 MHz Delay < 1.2 µs < 1.2 µs < 1.2 µs < 1.2 µs Pulse energy in cavity 0.1 mj 0.6 mj 3.5 mj 40 mj Avg. number of reflections ( ν ν ) = 5 µp 10 6 and ( ν ν ) = 7 µ He ν µp = 0.22 GHz and ν µ He + = 2.2 GHz. Narrow lines: Difficult to find the line Sub-ppm accuracy require little statistics A. Antognini PSAS 2016, Jerusalem p. 15

22 Systematics =0 A. Antognini PSAS 2016, Jerusalem p. 16

23 The laser systems 2 kw pump 969 nm µp Disk laser multi pass oscillator (regenerative amplifier) 400 mj, 250 Hz, pulse length ns cw diode laser 1030 nm 1030 nm OPO+OPAs cw diode laser tunable, 1785 nm 2434 nm 1785 nm DFG 6.7 µ m 1 mj µhe 1 kw pump 2 kw pump 969 nm 969 nm Disk laser oscillator 60 mj, 30 ns, 500 Hz cw diode laser 1030 nm 1030 nm Multi pass disk amplifier 400 mj 1030 nm SHG 515 nm OPO+OPAs cw diode laser tunable, 930 nm 930 nm 50 mj Needs to develop cutting-edge thin-disk laser technologies Needs to develop cutting-edge parametric down-conversion stages A. Antognini PSAS 2016, Jerusalem p. 17

24 The multi-pass cavities N = 1 1 L tot L tot = L ref + L hole + L scat + L defect N L tot λ challenge µp µm cryogenics µ 3 He nm 50 mj pulses A. Antognini PSAS 2016, Jerusalem p. 18

25 µz atoms Properties: - H-like atoms (electrons can be neglected) - MeV transition frequencies - MeV finite size effects Measure: - X-ray emitted during the muonic cascade - using high-resolution Ge detectors Complications: -nuclearpolarizability -nuclearexcitation during the cascade A. Antognini PSAS 2016, Jerusalem p. 19

26 µz atoms: motivation Atomic parity violation in Ra: - Measure E1 admixture in E2 transition Weinberg angle with 5 fold improvement over Cs - Charge radius with 0.2% rel. accuracy needed Measure radioactive nuclei (only µg allowed): - most of the stable nuclei already measured charge radii with rel. accuracy - some radioactive nuclei measurable with our low-energy µ beam line Atomic parity violation with muons (speculative) A. Antognini PSAS 2016, Jerusalem p. 20

27 Motivation, summary, outlook Test of H energy levels Bound-state QED Mu= µ + e Ps= e + e New physics? Parity violation? Scattering e + p e + p e + d e + d µ + p µ + p γ + p γ + p e + Z e + Z... Fundamental constants H, He, H + 2 spectroscopy r p, r d, r He EFT, χpt, lattice few-nucleon th. high-z radii quadrupole mom. mean-field nucl. th. magnetic radii µp, µd, µ He + (2S-2P) high-z muonic atoms (radioactive) HFS in µp andµ He + A. Antognini PSAS 2016, Jerusalem p. 21

28 Motivation, summary, outlook Test of H energy levels Bound-state QED Mu= µ + e Ps= e + e New physics? Parity violation? Scattering e + p e + p e + d e + d µ + p µ + p γ + p γ + p e + Z e + Z... Fundamental constants H, He, H + 2 spectroscopy r p, r d, r He EFT, χpt, lattice few-nucleon th. high-z radii quadrupole mom. mean-field nucl. th. magnetic radii µp, µd, µ He + (2S-2P) high-z muonic atoms (radioactive) HFS in µp andµ He + A. Antognini PSAS 2016, Jerusalem p. 21

29 CREMA collaboration F. Biraben, P. Indelicato, L. Julien, F. Nez Labor. Kastler Brossel, Paris M. Diepold, T.W. Hänsch, J. Krauth, R. Pohl, T. Kohlert MPQ, Garching, Germany F.D. Amaro, L.M.P. Fernandes, C.M.B. Monteiro, J.M.F. dos Santos J.F.C.A. Veloso Uni Coimbra, Portugal Uni Aveiro, Portugal M. Abdou Ahmed, T. Graf, IFSW, Uni Stuttgart A. Antognini, M. Hildebrandt, K. Kirch, A. Knecht ETH & PSI, Switzerland F. Kottmann, E. Rapisarda, K. Schuhmann, D. Taqqu Y.-W. Liu N.T.H. Uni, Hsinchu, Taiwan P. Amaro, J. Machado, J.P. Santos Uni Lisbon, Portugal A. Antognini PSAS 2016, Jerusalem p. 22