Mitglied der Helmholtz-Gemeinschaft The ANKE Experiments at COSY: physics program and technical development (including future plans) Andro Kacharava (IKP, FZ Jülich) June 25, 2012 | ANKE/PAX SPIN Physics Workshop

Outline  Introduction  Current status of program: Experiments using polarized beams and/or targets NN scattering program Selected results (pp/pn)  Near future: Double-polarized measurements for NN program Towards longitudinally polarized beams – pion program  Time line  Beyond ANKE Experiments at COSYAndro Kacharava

ANKE TOF WASA Introduction – COSY Facilities Hadron physics with hadronic probes Experimental set-ups:  ANKE  WASA  EDM (BNL/JEDI)  PAX  TOF (ext.) PAX EDM … the machine for hadron spin physics Andro Kacharava ANKE Experiments at COSY 3

 Precision / Schottky  Luminosity (target density)  Spin manipulation / RF  Precise momentum determination, dipole, solenoid systematics  Cooling / e-cooler,  Beam quality stochastic  Low momentum recoils  On-line polarimetry, Spectator detection effective neutron-target  Thin targets  Signal-to-background ratio Gas jet, very thin foils  Dense targets  Small x-section measurements Cluster, pellet  Large acceptance (near th.)  Calibration of spectrometer 2-body kinematics .... ANKE/COSY – Advantages of Internal Exp.‘s Feature / Technique  „Good for“ (examples) 4

→ PIT ANKE STT COSY: Tools at ANKE Andro KacharavaANKE Experiments at COSY 5

Andro KacharavaANKE Experiments at COSY6 Technical developments: PIT/STT Openable cell (target density) 4 STT modules Snake concept

Andro KacharavaANKE Experiments at COSY7 Technical developments: PIT status Polarized deuterium (ABS) target: test measurements at ANKE using the Lamb-Shift polarimeter (recent results - May 2012)

Andro KacharavaANKE Experiments at COSY8 Technical developments: Snake concept Should allow for flexible use at two locations Fast ramping (< 30s) Cryogen-free system B  dl (Tm) pn→{pp} s π - at 353 MeV3.329 PAX at COSY 140 MeV1.994 PAX at AD 500 MeV4.090 T max at COSY 2.88 GeV ANKE PAX ANKE

Physics program: Overview Andro KacharavaANKE Experiments at COSY9 Since 2005 ANKE has been equipped with a Polarized Internal Target (PIT) and embarked to measure the SPIN dependence of many polarized reactions : New insight into the strong interaction physics at intermediate energies ! ► Described in ANKE SPIN document: COSY proposal #152, “Spin Physics from COSY to FAIR” (nucl-ex/ ) 1. NN scattering ↔ Nuclear forces 2. Meson production ↔ ChPT, phenomenological models, FSI 3. Hyperon production ↔ SU(3) symmetry See talks: “Pion program” – S. Dymov “Eta-meson” – M. Papenbrock “Hyperon production” – Yu. Valdau “Kaon-pair production” – A. Dzyuba

Physics program: Present status Andro KacharavaANKE Experiments at COSY10 Performing single and double polarization experiments; 2 weeks run conducted last week (June 2012) on: ► “Initial research with polarized deuterium target” (exp.201) Preparing approved (un)polarized measurements (PAC #40): ► “NN elastic scattering up to maximum COSY energy” (exp. 212) ► “Measurement of quasi-free pn→dη reaction” (exp.211) ► “Initial research with longitudinal polarized proton beam” (exp.213) Data analysis of previous (un)polarized experiments !

NN program: pp elastic Description of nucleon-nucleon interaction requires precise data for Phase Shift Analysis COSY-EDDA collaboration produced wealth of data for pp elastic scattering. There are no experimental data at low angles (θ cm <30°) above 1.0 GeV energy. A y (pp) d  /d  (pp) ANKE EDDA Andro Kacharava ANKE Experiments at COSY11

NN program: np system R. Arndt: “Gross misconception within the community that np amplitudes are known up to a couple of GeV. np data above 800 MeV is a DESERT for experimentalists.” A yy (np) d  /d  (np) np forward np charge-exchange ANKE np forward np charge-exchange ANKE is able to provide the experimental data both for pp and np systems and improve our understanding of NN interaction Andro Kacharava ANKE Experiments at COSY ANKE 12

Andro KacharavaANKE Experiments at COSY13 COSY: Polarization observables in np scattering Experimental program: NN interaction Terms can be separated by measuring with polarised beams/targets: Unpolarised cross section d and p vector analysing powers d tensor analysing powers d-p vector spin correlations d-p tensor spin correlation Unpolarised intensity depends only upon spin-flip amplitudes: D.V.Bugg & C.Wilkin., Nucl.Phys.A467 (1987) 575

dp → (pp)n T n = 600 MeV → dp → (pp)n T n = 600 MeV → To check the feasibility of the program first experimental data was taken with deuterium beam at T n = 600 MeV to compare with tested theoretical predictions: D. Chiladze et al., PRST-AB 9, (2006) D. Chiladze et al., PLB 637, 170 (2006) D. Chiladze et al., EPJ. A 40 (2009) np study: Proof of principle D.V.Bugg & C.Wilkin., Nucl.Phys.A467 (1987) 575 Andro Kacharava ANKE Experiments at COSY dp → {pp} 1 S 0 n → 14

Status of np program: Analysing powers T n = 800 MeV T n = 900 MeV Results differ from theory at T n =1150 MeV, especially for low transferred momentum region T n = 1150 MeV D. Mchedlishvili et al., JP-CS, 295, (2011) Preliminary Andro Kacharava ANKE Experiments at COSY dp → {pp} 1 S 0 n → 15

Status of np program: Spin correlations C x,x C y,y T n = 600 MeV Relative phases between the amplitudes C x,x C y,y T n = 1150 MeV dp → (pp) 1 S 0 n → → Preliminary Andro Kacharava ANKE Experiments at COSY 16

Status of np program: dp → {pp}Δ 0 T n = 800 MeV T n = 900 MeV T n = 1150 MeV dσ/dm D. Mchedlishvili et al., JP-CS, 295, (2011) T n = 800 MeV T n = 900 MeV T n = 1150 MeV Preliminary Andro Kacharava ANKE Experiments at COSY 17

Status of pp program: Frequency shift  Beam-target interaction gives energy loss that changes the machine frequency.  Frequency change depends on η parameter  Schottky distribution was recorded in every 10 sec. throughout the 300 sec. cycle Revolution Frequency [kHz] Spectral Density of Schottky Power [arb. units] 10 sec. 80 sec. 150 sec. 220 sec. 290 sec. Cycle time Revolution Frequency [kHz] T 0 = 1.0 GeV (η>0) T 0 = 2.0 GeV (η<0) Mean frequency Exp. #200 Andro Kacharava ANKE Experiments at COSY 18

Status of pp program: Luminosity Cycledf/dt Target Density Integrated Luminosity e e e e e e e e With 2-3 % accuracy Exp. #200 Andro Kacharava ANKE Experiments at COSY 19

Status of pp program: Cross section  Only FD system is used.  Reconstructed missing mass of the proton ≈ 938 ± 18 MeV ° ° ° T p = 1.0 GeV T p = 2.0 GeV T p = 2.8 GeV SAID  ANKE Preliminary SAID  ANKE SAID  ANKE Exp. #200 Andro Kacharava ANKE Experiments at COSY 20

Near future: Two examples Next PAC meeting (#41)  Double-polarized measurements for NN sector (Exp.“212.1“) requirements: pol. beam, pol. target (D), 4 STT‘s, openable cell, roughly ~ 7-8 weeks of BT  A xz measurement for pion production (Exp. “213.1“) requirements: + roughly ~ 10 weeks of BT  Synergy (and coordination) with PAX and TRIC Exp.‘s ! Andro KacharavaANKE Experiments at COSY21

Time line: up to 2014 ↓___↓____________________↓__ 2012 PAC#40 Exp. 201 Snake delivery ____ ↓ ____I ANKE BT I ___ ↓ __________________↓________ 2013 Snake Exp.s: 211, 212 PAC#41 Double-pol. (Exp. PAX ____↓_____________↓_____________↓__________↓_ 2014 Exp (A xz ) PAC#42 Double-pol. (Exp.#???) 22ANKE Experiments at COSY Andro Kacharava

Time line: beyond 2014 Examples (PAC #42):  Explore longitudinal polarized beam for spin observables in NN sector  Develop concept and start to create polarimetry data base for the COSY EDM project via measurement of spin dependence of the pp, pd and dp elastic processes  Strangeness production – (Λn) scattering length: singlet (a s ) and triplet (a t ) part separately via spin correlation parameter (C yy ) measurements ( ► depends on TOF result on Λp system) 23ANKE Experiments at COSYAndro Kacharava

The END Many thanks to the workshop organizers ! 24

The END 25

Andro KacharavaANKE Experiments at COSY26 Spare transparencies

ΛN scattering length: singlet (a s ) and triplet (a t ) part separately Spin/isospin dependence TOF: high-resolution single polarized p+p→K + (Λp) at (θ K,cm = 90°)  a t ANKE: double polarized p+n→K + (Λn) (1 – C NN )·σ at (θ K,cm = 0°)  a s Strangeness production: YN Interaction Poor data base: -  N little known -  N nothing known YN scattering experiments difficult  large uncertainty in  p scattering length Theory Model-free determination in production reactions Method: dispersion relations Theory precision is 0.3 fm → →→  A. Gasparyan et al., PRC 69, (2004) Andro Kacharava26ANKE Experiments at COSY

Mitglied der Helmholtz-Gemeinschaft   COSY proposal #152 ArXiv:nucl-ex/