Hartmut Machner, MENU04 Beijing 1 Physics at COSY - up to 3.6 GeV/c - e and stochastic cooling, -...

Hartmut Machner, MENU04 Beijing

1

Physics at COSYPhysics at COSY- up to 3.6 GeV/c

- e and stochastic cooling,

- stochastic extraction (10 s - min)

- luminosity achieved: L = 1032 cm-2s-1

- p and d beams - (cooled) beam quality: = 0.4 mm mrad ( = 0.5 mm ) ~0.1% halo at = 2.5 mm

p/p = 510-5

- close to target tracking

- p vector polarised

- d vector and tensor polarised


2

Detectors: Time-of-Flight Detectors: Time-of-Flight Detector TOFDetector TOF

K+

p

p

-

- barrel and forward scintillators- forward calorimeter- start detector- excellent tracking capability- ~2 acceptance (lab)


3

Germaniumdetector

Detectors: Big KarlDetectors: Big Karl

• focussing spectrometer ( = 10 msr)• high resolution p/p < 510-5

• combined with detectors close to target:• multi-layer Germanium detector GEM


4

Detector Systems at the Detector Systems at the Internal BeamInternal Beam

EDDA, PISA– Non-magnetic detectors

ANKE, COSY-11– Magnetic spectrometer

– COSY-11

• uses a COSY dipole

– ANKE: • chicane with one

movable dipole

Employed Targets: – Strip– Cluster– Polarized Atomic (ABS)– (Pellet)

EDDA

COSY-11

ANKE

PISA


5

Selected topicsSelected topics

• pp pK

• pp pp K+K-

• pp d K+K0 (d a0(980))

• pA KX

• pd 3He K+K- (3He )

• pp

strangeness productionstrangeness production threshold production, symmetries, precision experiments

• p, ’ production in pp and p+d reactions

• production

•isospin symmetry

• mass precision experiment

•pn FSI in production


6

Comparison to TheoryComparison to Theory


7

Hyperon ProductionHyperon Production

_Strangeness degree of freedom:

- ss creation

- interaction of strange hadrons

Model

reconstructed

TOF p p Y N K ( Y = , )

p n Y N K

K Y

N Y

K N

N*

aYN

exotics

TOF Exp.

N*

N - FSI


8

Evidence for Evidence for

hyperon production: p p p K0 +

+ (pentaquark) production: p p + + p K0 +

- no acceptance cuts

- complete reconstruction of final state

- M = 15305 MeV/c2

- 18 MeV/c2

- large cross section: = 0.40.1stat0.1syst b

M. Abdel-Bary et al. , Phys. Lett. B


9

++ observations observations

u

du

12

12

K n configuration

dn

K+

u

du

12

12

diquark – triquark configuration of the uudds pentaquark

d


10

ppppdKdK++KK00

non-resonant resonantV. Yu. Grishina, EPJ


11

pdpd33He KHe K++KK--

BK acceptancebeam

K+

K-

vertex wall

3Hep

LD2 target

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

( n

b )

0 5 10 15 20 25 (MeV)

pd3He

0

2

4

6

8

10

12

14

16

18

20

22

(n

b)

0 10 20 30 40 50 60 (MeV)

pd3HeK+K-

s-wave !


12

dpdp33He He Q=28 MeV

p-wave!


13

ssss in the Nucleon in the Nucleon

meson production

p p p p +-0

ratio R =p p p p

p p p p

= s s production suppressed

strangeness content of the nucleon

DISTO: (pp pp)/(pp pp) at fixed incident energy

TOF: (pp pp) at identical excess energy R = (31)10-2 OZI rule: R = 410-3

_

TOF

_


14

and and ’ Production’ Production

phase space

+ pp fsi

+p fsi

3P01S0s

3P01S0s

+ 1S03P0s

+ 1D23P2s

importance of N* N+production!


15

pdpd33HeHe

102

103

| f|2 (

n b)

0.0 0.5 1.0 1.5 2.0 2.5 3.0

q (fm-1)

SPES IICOSY 11 prelim.SPES IVWASAGEMBanaigsKirchnerKoukazSibirtsev et al.

2

2 2 22

| | | | | |p

k df f T q

q d


16

0- meson mixing

dduu|2

1~| 0 ssdduu 2|6

1~|

ddmuumH du + (isospin symmetric interaction) + (electromagnetic interaction)

Isospin Symmetry Breaking Isospin Symmetry Breaking and Quark Massesand Quark Masses

~|cos~|sin|

~|sin~|cos|0

00 0||0 H

22

0

0

~||~

mm

H


17

simple model for reactions close to threshold[A. Magiera & H. Machner, NP A674(2000)515]

dp

03 ~He

~3 He

03 He

0T

T

1

dp H3

02

TT

cos||||21

2

003

3

TTp

p

dd

ddR

He

H

- relative phase of

0T and T

interference effect

dd ~4 He 04 HeT

d

d

p

p

d

d

200

charge symmetry breaking


18

T

Isospin symmetryIsospin symmetry

• Magiera & Machner model =0.006±0.005

• Green & Wycech (K-Matrix formalism: pd3He+t 3Hepd t= 0.010±0.005

• Baru et al: strong fsi of the virtual -3He system

•Tippens et al. = 0.026±0.007


19

pdpd33A+A+

10-4

10-3

10-2

10-1

100

10-3

10-2

10-1

100

1.0 1.5 2.0 2.5 3.0 3.5

pp (GeV/c)

GEM (magnet)GEM (wall)LANLKerboulNikulinPickarCameronBerthet

d/d b/s

r)

p+d3H+

p+d3He+

N*(1535)

10-2

10-1

100

d /d b /s r

)2900 3000 3100 3200 3300 3400 3500

sqrt(s) MeV/c2

GEM (magnet)GEM (wall)Berthet+

Kerboul (*2)0 (*2)

p+d3A+ deg

-resonance with momentum dependent width

Barry model


20

Breit Wigner Breit Wigner parametrisationparametrisation

2

,res02

2p ,res

res

p ppd a / 4; 1 b

d p ps s / 4

reactiona

(b/sr)b

(MeV)

sres1/2

(MeV)

sres1/2-2*mp

(MeV)

3He+0 6.16±0.68 -0.55±0.07 168±20 3111±9 1234±9

3H++ 11.4±1.5 -0.64±0.05 164±25 3113±4 1236±4


21

New determination of theNew determination of the -mass-mass

three reactions simultaneously:

3

3

3

H

p d H

He

first two reactions calibrate magnetic spectrograph and beam momentum (self calibrating)


22

resultresult m = 547.257 0.044 MeV/c2


23

Pole and continuumPole and continuum

101

102

103

104

c ou n

ts/ 0

. 2 M

eV

-5 0 5 10 15 20 (MeV)

ppd

pppn

2dpp pn

d dxd

pp d R xd

xB

Boudard, Fäldt & Wilkin:

works at smaller beam momenta

=0 degree, pp=1640 MeV/c

100 keV resolution!


24

pn-fsipn-fsi

0

100

200

300

400

c ou n

ts/ 0

. 2 M

eV

-2 0 2 4 6 8 10 12 14 16 18 20 22 (MeV)

0

100

200

300

400

c ou n

ts/ 0

. 2 M

eV

-2 0 2 4 6 8 10 12 14 16 18 20 22 (MeV)

spin triplet, isospin singlet

a= +5.396 fm

r0= 1.726 fm

spin singlet, isospin triplet

a= -23.678 fm

r0= 2.51 fm


25

pd Dynamicspd DynamicsSurprisingly large Ay

p in pd (pp)s n

Effect shows strong energy dependence

Epp < 3 MeV

Epp < 3 MeV

p d

pp

n

θcm~166o

?

pd dynamics at high momentum transfer

– pd (pp)s n– Kinematics like pd backward elastic

→ S-wave pp-pairs→ Suppression of

– Progress– cross sections ()– Analyzing Power Ay

p ()– Future: Polarized target

– Analyzing Power T20

– Spin-Correlation Parameters


26

SummarySummary

•COSY has unique beam properties: emittance, resolution, polarization

•Instruments are complementally to each other: acceptance, resolution

•Convincing physics program

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Hartmut Machner, MENU04 Beijing 1 Physics at COSY - up to 3.6 GeV/c - e and stochastic cooling, -...

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