Search for charged particle Electric Dipole Moments in storage rings

Transcription

1 Mitglied der Helmholtz-Gemeinschaft Yur Senichev Search for charged particle Electric Dipole Moments in storage rings on behalf of Collaboration JülichElectricDipole moment Investigation 8. November 06

2 Electric Dipole Moment and Standard Model Within the framework of the Standard Model, the reasons for the violation of the CP smmetr is still not understood. But CP violation is the onl known mechanism (A.D. Sakharov) that could explain the matter-antimatter asmmetr found in Universe. The electric dipole moments (EDM) of fundamental particles are excellent probes of phsics beond the standard model (SM), e.g. SUSY, since the allow for values within experimental reach whereas the SM predictions are several orders below them. 8. November 06 Folie

3 First message to search for Electric Dipole Moments(EDM) of fundamental particles: it came to understand the CP violation Second message for Electric Dipole Moments of fundamental particles: the baron asmmetr of the Universe that represents the fact of the prevalence of matter over antimatter In 967 A.Sakharov has shown three necessar conditions for barogenesis (initial creation of barons) Baron number violation; C-smmetr and CP-smmetr violation; Interactions out of thermal equilibrium The analsis done b the AD Sakharov, showed that this CP-violation is absolutel necessar to explain wh on earth and in the visible universe there is a MATTER, but there is practicall no ANTIMATTER. 8. November 06 Folie 3

4 Current results for neutron: 8. November 06 Folie 4

5 Current achievements in EDM measurement for fundamental particles: 8. November 06 Folie 5

6 Storage Ring EDM Project Options: Electric ring (proton or electron): onl E-field Electro-magnetic field ring (deuteron): E- and B-fields JEDI Jülich Electric Dipole Moment Investigations JEDI-Collaboration 8. November 06 Folie 6

7 Cooler Snchrotron COSY Siberian Snake MV Electron Cooler Ions: (pol. & unpol.) p and d Momentum: 300/600 to 3700 MeV/c for p/d, respectivel Circumference of the ring: 84 m Electron Cooling up to 550 MeV/c Stochastic Cooling above.5 GeV/c 8. November 06 Folie 7

8 Basic principle of EDM measurement in ring comes from Thomas-Bargmann, Michel,Telegdi equation with EDM term The spin is a quantum value, but in the classical phsics representation the spin means an expectation value of a quantum mechanical spin operator: d S dt S e GB G m g G, G E EE B is theanomalousmagneticmoment, g is thegromagnetic ratio d e e / 4 mc e m 938.7MeV MeV sec.9979m/sec 4d mc 5 ec e EDM 0 8. November 06 Folie 8

9 Two conceptions of ring for proton and deuteron EDM search:. Resonant method based on RF flipper. Frozen spin method 8. November 06 Folie 9

10 In resonant method* for p and d (W.Morse, et al.,) the spin frequenc is parameterized : E E B e GB G m using RF field E ~ e. In case of parametric resonance when observe the resonant build up: S z ( n) h ( e s h s) sinsn hn cos sn E l rf rf B L cir s ~ EDM signal i( Advantage: the method can be realized in COSY ring e Disadvantage: the high requirement to stabilit of f rf and slow process frf kfrev) t s G f f rf rev B S p x z E x k G; k 0,,,... T - period of envelope B RF field we shall T f -peiod of fundamental oscillation Sz max 8. November 06 Folie 0

11 8. November 06 Folie Frozen spin method for purel electrostatic proton ring at magic energ In the FS method the beam is injected in the electrostatic ring with the spin directed along momentum S p and S E; S={0,0,S z} and E={E x,0,0} at magic energ :, g G B E E G GB m e S dt d S E G B G MDM spin frequenc EDM spin frequenc 0 G mag B

12 8. November 06 Folie Frozen spin method for purel electrostatic proton ring at magic energ In the method the beam is injected in the electrostatic ring with the spin directed along momentum S p and S E; S={0,0,S z} and E={E x,0,0} at magic energ :, g G B E E G GB m e S dt d S E G B G MDM spin frequenc EDM spin frequenc 0 G mag B

13 8. November 06 Folie 3 Frozen spin method for purel electrostatic proton ring at magic energ In the method the beam is injected in the electrostatic ring with the spin directed along momentum S p and S E; S={0,0,S z} and E={E x,0,0} at magic energ :, g G B E E G GB m e S dt d S E G B G MDM spin frequenc EDM spin frequenc 0 G mag

14 Frozen spin method for purel electrostatic proton ring at magic energ In purel electrostatic ring the spin of particle with magic energ rotates with the same angular frequenc as the momentum and it tilts up in the YZ plane due to the EDM with angular rate d S e m E Sdt p S z ARC x B =0 electrostatic field E x S p EDM ARC 8. November 06 Folie 4

15 EDM growth in FS concept 8. November 06 Folie 5

16 EDM growth in FS concept 8. November 06 Folie 6

17 EDM growth in FS concept 8. November 06 Folie 7

18 8. November 06 Folie 8 Frozen spin method for deuteron: Frozen spin lattice for deuteron based on the «B+E» elements: - the spin of the reference particle is alwas oriented along the momentum 0 x z E c G GB c GB E x MDM

19 Sensitivit of EDM experiment 8. November 06 Folie 9

20 To design the new EDM ring we should solve the next problems 8. November 06 Folie 0

21 Frozen Spin lattice for deuteron The condition of the zero MDM spin precession frequenc in FS lattice [,] z MDM GB G 0 Ex c creates the relation between E and B fields in incorporated bending elements: E r GBc Frozen Spin lattice based on B+E elements and TWISS functions 8. November 06 Folie

22 Spin tune coherence In magnetic field In electric field B MDM E MDM G 3 G ( G) / ( G) / i S i ( t t ) 0 decoh 8. November 06 Folie

23 8. November 06 Folie 3 Spin tune coherence : RF field as a method for mix particles of energ t snch m cos G E evh s s s z ˆ

24 8. November 06 Folie 4 Spin tune coherence: 3D dependence Equation of Longitudinal motion: x and orbit lengthening nonlinear term of energ oscillation E h ev dt d L L dt d rf rf rf nonlinear term of energ oscillation x and orbit lengthening Nonlinear Z motion Betatron motion L L s s m s s eq 4 0 0

25 Spin tune coherence: sextupole correction, sext S sext D L 3 0 0, sext 4 s s 0 L L sext S sext D 0x, x, L 8. November 06 Folie 5

26 Spin tune coherence: COSY ring experiment 8. November 06 Folie 6

27 Quasi-Frozen Spin (QFS) method for deuteron From T-BMT equations follows that the growth of the EDM signal is directl dependent on the angle between the spin and momentum direction. Exact fulfillment of the frozen spin condition is not required. We need an equal deviation of spin in magnetic and electric fields totall on the ring To realize the quasi-frozen spin concept, we have to fulfil the condition: B ss spin E ss spin B arc spin B ( G ( G ) ss p G p G G p E ss p G G p B arc p G The basic relations are: mc ss 3 L E Bss ss G e c 8. November 06 Folie 7 E

28 dedm growth: 3D spin orbital simulation b MODE and COSY Infinit codes η = 0-5 Results of 3D spin-orbital simulation: - Due to Sx oscillation (QFS) the EDM signal decreases b % - In each magnet EDM signal grows b *0-6 and in each deflector b *0-7 - Total EDM signal grows b *0-5 per turn - In order to get total EDM signal ~0-6 we have to keep the beam in ring during N turn ~0 9 or ~800 sec 8. November 06 Folie 8

29 QFS lattice In QFS lattice we introduced a magnetic field of small value ~80 mt, compensating the Lorentz force of the electric field in electrostatic deflector located on the straight sections. Ring lattice based on QFS concept: ring view with main elements and TWISS functions r r R r eq 0 d x eu 0 ds mv d d 0 ds 8. November 06 Folie 9

30 Spin decoherence in FS and QFS 8. November 06 Folie 30

31 QFS in COSY ring In precursor experiment we do not need a large statistics and we can start working on energ 75 MeV. This allows to use onl 4 E+B straight elements, which is four times less than at 70 MeV. The total length is x7 m. Further, E+B elements can be used for a full scale experiment at 70 MeV. In result, it will provide Quasi Frozen Spin at energ of 75 MeV. Due to small B field value the E+B elements on the straight sections ma be made using ordinar electrical coils with field 0-00 mt. The condition for spin recover is fulfilled using E field (working regime <0 kv/cm).. QFS straight deflector with B fields S B=80 mt E=0 kv/cm beam N 8. November 06 Folie 3

32 Sstematic errors due to magnet rotation around the longitudinal axis (Bx 0 ΩBx, 0, Ω=<Ωdecoh>) For initial condition S x 0, S 0, Sz, z from T-BMT equations: S ( t) x ds S dt MDM sin( x x EDM 0 t) ; S ( t) x sin( x x t) ; x EDM 0 Bx decoh S x ( t) S ( t) sin( decoh Bx Bx sin EDM Bx ) t t; e m. Bx G GB x EDM 8. November 06 Folie 3

33 COSY Inf+MODE simulation of sstematic errors due to magnet rotation around the longitudinal axis Coherent component S ( t ) sin( ) t Bx EDM S x ( t ) decoh Bx sin Bx t Decoherent component 6/ N /( ~ T) N is the total number of useful events, ~ 0.7 is the oscillation amplitude of measured asmmetr of polarization, T is the measurement duration. detector rate of 5000 s For 6000 hours (one ear ) statistic error is 5 0 It means EDM value could be defined on the level e cm Parameters of decoherent component 8. November 06 Folie 33 8

34 The best wa to get rid of the enem - make him a friend, or how to use sstematic errors to measure EDM in CW+CCW procedure To split out the EDM signal from the sum signal we use CW+CCW procedure:. Calibration of Bx throught B. Measurement of the total spin frequenc in the experiment with a counter CW clock-wise (CW) direction of the beam CW Bx EDM 3. Installation of B field after the polarit change using calibration 4. Measurement of the total spin frequenc in the experiment with a counter CCW clock-wise (CCW) direction of the beam CCW Bx EDM 5. Compare CCW with clock-wise (CW) measurements EDM ( CW CCW CCW ) / ( CW CCW Bx ) / 6. The difference Bx Bx Bx determines the accurac of the EDM measurement. Calibrating Bx we can minimize up to value of calibration accurac. CW Bx 8. November 06 Folie 34

35 Bx and B calibration procedure First, we suggest calibrating the field of the magnets using the relation between the beam energ and the spin precession frequenc in the horizontal plane, that is, determined b the vertical component B. Since the magnet orientation remains unchanged, and the magnets are fed from one power suppl, the calibration of B will restore the component Bx with the same accurac 0^(-0), CCW CW that is the difference as well. Such procedure does not involve Bx Bx EDM signal. If we assume that we can measure the spin frequencies CW, CCW with an accurac of 0^(-0) alread experimentall demonstrated in COSY and reach the calibration accurac of Bx up to 0^(-0) we will be able to determine the EDM frequenc up to 0^(-0) rad/sec, which corresponds to the EDM measurement on the level of 0^(-9) 0^(-30) e cm the results of a numerical simulation of the EDM measurement procedure, we took the EDM 0^(-), that is 0.rad/ sec EDM 8. November 06 Folie 35

36 Bx coil Nevertheless, the fundamental question of how to calibrate the field B using the spin tune measurement in a horizontal plane, if due to misalignments the spin rotates in the vertical plane with relativel high frequenc ~0 rad/sec, remains. To solve this problem, we plan for the calibration time onl to introduce the inhibitor vertical field, for example b means of a horizontal coil. Having inhibited rotation in the vertical plane to the reasonable value of ~0. rad/sec and calibrated, then we turn off the coil. In this case we do not need to know the value of the field in the coil Nevertheless introducing the coil we can modif the integral value of the guiding magnetic field B. Let us estimate this value. We know that due to misalignment of magnets with an accurac of 0 micrometer, we have in Bx/B = 0 ^(-)6. Obviousl the coil can be installed with the same accurac and B(coil)/Bx(coil)=0^(-6). Thus, the coil introduces in B of ring 0^(-) 8. November 06 Folie 36

37 Sstematic errors due to magnet rotation around the transverse axis (Bz 0 Ωz, 0, Ω=<Ωdecoh>) The longitudinal component of field is most undesirable as it transforms the spin decoherence from the horizontal plane into the vertical plane where we expect a signal of EDM. The fake signal depends on the ratio between decoh and Bz ds S dt MDM EDM Because of the oscillations around the longitudinal axis the EDM signal periodicall changes the sign of growth. Therefore, the onl wa is to minimize the longitudinal component of the magnetic field with ~ 0 9 rad/turn Bz For initial condition Sx 0, S 0, Sz from T-BMT equations: S ( t) x sin( z S ( t) z z z cos( t) ; z t) ; z Bz 0 decoh S ( t) sin( x S ( t) Bz decoh Bz decoh decoh t); cos( decoh t) ; S x ( t) S ( t) Bz decoh decoh Bz decoh Bz sin( Bz t); cos( Bz t) ; MODE 3D simulation In the experiment, E. S. the vertical component increases 4 with rate ~ 0 rad/s 8. November 06 Folie 37

38 Storage Ring EDM Project pedm dedm Possibilit of a discover Highest sensitivit 8. November 06 Folie 38

39 COSY Infinit and MODE codes Spin-orbit dnamics of polarized beam investigated using: - the code COSY Infinit (M. Berz,Michigan State Universit, USA) - the code MODE (S. Andrianov and A. Ivanov St.Petersburg Universit). The algorithm of the MODE is based on an original idea of S. Andrianov and A. Ivanov 8. November 06 Folie 39

40 Conclusion 8. November 06 Folie 40

41 8. November 06 Folie 4