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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 2014

2ANKE 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 forhadron 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)Feature / Technique „Good for“ (examples)

4

→ PIT

ANKE

STT

COSY: Tools at ANKE

Andro Kacharava ANKE Experiments at COSY 5

Andro Kacharava ANKE Experiments at COSY 6

Technical developments: PIT/STT

• Openable cell (target density)

• 4 STT modules

• Snake concept

Andro Kacharava ANKE Experiments at COSY 7

Technical developments: PIT status

Polarized deuterium (ABS) target:

test measurements at ANKE

using the Lamb-Shift polarimeter

(recent results - May 2012)

Andro Kacharava ANKE Experiments at COSY 8

Technical developments: Snake concept

• Should allow for flexible use at two locations

• Fast ramping (< 30s)

• Cryogen-free system

Bdl (Tm)

pn→{pp}sπ- at 353 MeV 3.329

PAX at COSY 140 MeV 1.994

PAX at AD 500 MeV 4.090

Tmax at COSY 2.88 GeV 13.887

ANKE

PAXPAX

ANKE

Physics program: Overview

Andro Kacharava ANKE Experiments at COSY 9

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/0511028)

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 Kacharava ANKE Experiments at COSY 10

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 forpp elastic scattering.

•There are no experimental data at low angles (θcm<30°)above 1.0 GeV energy.

Ay (pp)

d/d (pp)

ANKE

EDDA

Andro Kacharava ANKE Experiments at COSY 11

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.”

Ayy (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 Kacharava ANKE Experiments at COSY 13

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:

221

31

3

4

, qkSIkdtd

d

2

0py

dy

AI

AI

22222

22222

22

2

RAI

RAI

yy

xx

2

2

,

,

xx

yy

CI

RCIpyyyy ACI 2,

qkSqkSR 21

21 ,, 22222

RI

llmmnnn pnpnpnpnnp if

D.V.Bugg & C.Wilkin., Nucl.Phys.A467 (1987) 575

dp→(pp)nTn = 600 MeV

→

dp→(pp)nTn = 600 MeV

→

To check the feasibility of the program first experimental data was taken with deuterium beam at Tn = 600 MeV to compare with tested theoretical

predictions:

D. Chiladze et al., PRST-AB 9, 050101 (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}1S0n

→

14

Status of np program: Analysing powers

Tn = 800 MeV

Tn = 900 MeV

Results differ from theory at Tn=1150 MeV, especially for low

transferred momentum region

Tn = 1150 MeV

D. Mchedlishvili et al., JP-CS, 295, 012099 (2011)

Preliminary

Andro Kacharava ANKE Experiments at COSY

dp→{pp}1S0n

→

15

Status of np program: Spin correlations

Cx,x

Cy,y

Tn = 600 MeV

Relative phases between the amplitudes

Cx,x

Cy,y

Tn = 1150 MeV

dp→(pp)1S0n

→→

Preliminary

Andro Kacharava ANKE Experiments at COSY 16

Status of np program: dp → {pp}Δ0

Tn = 800 MeV

Tn = 900 MeV

Tn = 1150 MeV

dσ/dm

dσ/dm

dσ/dm

D. Mchedlishvili et al., JP-CS, 295, 012099 (2011)

Tn = 800 MeV

Tn = 900 MeV

Tn = 1150 MeVPrelim

inary

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.

1548.201548.10 1548.30

Revolution Frequency [kHz]

Spe

ctra

l Den

sity

of

Sch

ottk

y P

owe

r [a

rb.

units

]

10 sec.

80 sec.

150 sec.

220 sec.

290 sec.

Cycle tim

e

1429.501429.45 1429.55

Revolution Frequency [kHz]

T0 = 1.0 GeV (η>0) T0 = 2.0 GeV (η<0)

Meanfrequency

Exp. #200

Andro Kacharava ANKE Experiments at COSY 18

Status of pp program: Luminosity

Cycle df/dtTarget Density

Integrated Luminosity

1 0.152 2.75e+14 1.67e+33

2 0.151 2.74e+14 1.76e+33

3 0.154 2.79e+14 1.81e+33

4 0.149 2.70e+14 1.68e+33

1 2 3 4

1 2 3 4

nT 1

1

dE dx mT0

f02

1

df

dt

Tp 2.0GeV

0.07

f0 1548.15kHz

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.

13 - 14° 20 - 21° 27 - 28°

Tp = 1.0 GeV

Tp = 2.0 GeV Tp = 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

Axz measurement for pion production (Exp. “213.1“)

requirements: + Snake@PAX, roughly ~ 10 weeks of BT

Synergy (and coordination) with PAX and TRIC Exp.‘s !

Andro Kacharava ANKE Experiments at COSY 21

Time line: up to 2014

↓___↓____________________↓__ 2012 PAC#40 Exp. 201 Snake delivery

____↓____I ANKE BTI___ ↓ __________________↓________ 2013 Snake Exp.s: 211, 212 PAC#41 Double-pol. (Exp. 212.1)

@PAX

____↓_____________↓_____________↓__________↓_ 2014 Exp. 213.1 (Axz) PAC#42 Double-pol. (Exp.#???) Snake@ANKE

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 (as) and triplet (at) part separately via spin correlation parameter (Cyy) 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 Kacharava ANKE Experiments at COSY 26

Spare transparencies

ΛN scattering length: singlet (as) and triplet (at) part separately

Spin/isospin dependence

• TOF: high-resolution single polarized

p+p→K+(Λp) at (θK,cm = 90°) at

ANKE: double polarized p+n→K+(Λn) (1 – CNN)·σ at (θK,cm = 0°) as

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, 034006 (2004)

Andro Kacharava 26ANKE Experiments at COSY

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COSY proposal #152 ArXiv:nucl-ex/0511028