DIRAC status π + K ‒ - and π ‒ K + -atoms π + π ‒ -atoms (   ) Run 2011 Future magnet   level scheme, Stark effect and energy splitting measurement 1 Leonid Nemenov 21. October 2011

I Status of π + K ‒ -atoms 2 Run , statistics with low and medium background (⅔ of all statistics). Point-like production of all particles. The e + e ‒ background was not subtracted. Q Q – relative momentum in the πK c.m.s. A. Benelli, V. Yazkov Coulomb pairs Atomic pairs non-Coulomb pairs

II Status of π - K + -atoms 3 Run , statistics with low and medium background (⅔ of all statistics). Point-like production of all particles. The e + e ‒ background was not subtracted. A. Benelli, V. Yazkov Q – relative momentum in the πK c.m.s. Coulomb pairs Atomic pairs non-Coulomb pairs

III. The status of π - K + and π + K ‒ atoms 4 A. Benelli, V. Yazkov Run , statistics with low and medium background (⅔ of all statistics). Point-like production of all particles. The e + e ‒ background was not subtracted. Q – relative momentum in the πK c.m.s. Coulomb pairs Atomic pairs non-Coulomb pairs

IV Status π + π ‒ -atoms 5 Run , statistics with low and medium background (⅔ of all statistics). Point-like production of all particles. The e + e ‒ background was not subtracted. Coulomb pairs Atomic pairs non-Coulomb pairs A. Benelli, V. Yazkov Coulomb pairs Atomic pairs non-Coulomb pairs

V Status of 2011 run 6 Neodymium magnetic piece=70x60x5mm 3 : Gap=60mm; BL=0.01Tm Time of delivery to CERN: before 4 May 2011 y z x 150mm 90mm 60mm Tokyo Metropolitan University & Kyoto University

Simulation of long-lived A 2π observation V. Yazkov Without magnetWith magnet after Be target 7

Coulomb peak of π + π ‒ 8 Shift because of magnet degradation !

Shift of Q y (June-August) π + π ‒ data 9

Q x distribution (B x =0) 10 F. Takeutchi, V. Yazkov

Shift of Q y (June-August) e + e ‒ data Pairs generated after magnet Pairs generated on Be target before magnet F. Takeutchi, V. Yazkov 12

Shift of Q y (June-August) e + e ‒ data without central peak 12 e + e ‒ generated on Be target before magnet F. Takeutchi, V. Yazkov

Shift of Q y (August-September) e + e ‒ data without central peak 13 F. Takeutchi, V. Yazkov

VI STATUS OF THE FUTURE MAGNET Halbach configuration NdBFe or SmCo 60 x 60 bore B = 0.89 T The magnets cost about $. The fabrication time is about 65 days. Y. Iwashita 14 flat

Y. Iwashita By along z-axis 15

V. Brekhovskikh Current Magnet Holder 16

The New Magnet Holder Y. Iwashita 17

A 2π Energy Levels J. Schweizer (P. L. 2oo4) For Coulomb potential E depends on n only. CONCLUSION: one parameter (2a 0 +a 2 ) allows to calculate all Δ ns-np values. VII ENERGY SPLITTING MEASUREMENT 18

Coulomb bound state and strong & electromagnetic perturbation DGBT *) formula & numerical values: A) Energy shift contributions: ______ *) Deser, Goldberger, Baumann, Thirring, PR 96 (1954) 774. B) Decay width: with Remark S-wave scattering lengths are amplitudes at threshold: em shiftstrong shift vacuum polarization 19 and

A 2π level scheme and 2s – 2p energy splitting n=1 n=2 n= E n (keV) ε 1s Γ 1s ε 2s Γ 2s Stark mixing J. Schacher 20 ΔE 2s-2p

Values for energy shifts and lifetimes of π + π − atom [J. Schweizer, PL B587 (2004) 33] *) J. Schacher 21

CERN, Geneva - Monday 26, September, 2011 M. Pentia nHnH τ H 10 8 sτ 2π s Decay length A 2π in L.S. cm for γ=16.1 2p p p p p p 46.8 * 226 8p 69.3 * 335 A 2π lifetime, τ, in np states * - extrapolated values 22

L. Afanasev; O. Gorchakov (DIPGEN) Atomic pairs from A 2π long-lived states breakup in 2μm Pt. Long-lived A 2π yield and quantum numbers 23

24 Impact on atomic beam by external magnetic field B lab and Lorentz factor γ ++  See: L. Nemenov, V. Ovsiannikov, Physics Letters B 514 (2001) 247. …. relative distance between  + and   in A 2  system …. laboratory magnetic field …electric field in A 2  system Lamb shift measurement with external magnetic field

L. Nemenov, V. Ovsiannikov [PL B514 (2oo1) 247] F … strength of electric field in A 2π c.m.s. → m must be 0 B L  B lab in lab system CONCLUSION: the lifetimes for long-lived states can be calculated using only one parameter → E 2s -E 2p. The lifetime of A 2π in electric field 25

A 2π * (2p-state) lifetime versus electric field Atom-field interaction: with J. Schacher 26 …will change => [weak-field limit]

 H=0.4 T H=0.6 T H=0.8 T H=1.0 T H=1.2 T H=1.4 T H=1.6 T H=0.0 T  =1 N A =330 ± 40 H=0.1 T  =1 N A =330 (1-0.7%) 27 V. Brekhovskikh

Magnetic Field T 28 2p3p4p5p6p7p8p∑ n,%  ∙10 -11,s L,cm  n  eff ∙10 -11,s L eff,cm NaNa N a eff Magnetic Field 1.0 T  = 40% p3p4p5p6p7p8p∑ n,%  ∙10 -11,s L,cm  n  eff ∙10 -11,s L eff,cm NaNa N a eff Magnetic Field 1.0 T  = 100% p3p4p5p6p7p8p∑ n,%  ∙10 -11,s L,cm  n  eff ∙10 -11,s L eff,cm NaNa N a eff ∙ Magnetic Field 1.0 T  = 160% CERN, Geneva - Monday 26, September, 2011 V. Brekhovskikh

29

Reserve: 30

External magnetic and electric fields Atoms in a beam are influenced by external magnetic field and the relativistic Lorentz factor. 31

L. Nemenov, V. Ovsiannikov (P. L. 2oo1) F – strength of electric field in A 2π c.m.s. → m must be 0 B L in lab. syst. CONCLUSION: the lifetimes for long-lived states can be calculated using only one parameter → E 2s -E 2p. The lifetime of A 2π in electric field 32 mmmmmmmmmm m