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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.)
PAXEDM
… 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.‘sFeature / 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 systemR. 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 scatteringExperimental 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 MeVPreliminary
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 1548.30Revolution Frequency [kHz]
Spe
ctra
l Den
sity
of S
chot
tky
Pow
er [a
rb. u
nits
] 10 sec.
80 sec.
150 sec.
220 sec.
290 sec.
Cycle tim
e
1429.501429.45 1429.55Revolution 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/dt Target 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
1dE dx m
T0
f02
1dfdt
Tp 2.0GeV 0.07f0 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
SAIDANKE
Preliminary
SAIDANKE
SAIDANKE
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 !
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The END
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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