Post on 12-Jan-2016
transcript
Hartmut Machner, MENU04 Beijing
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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
Hartmut Machner, MENU04 Beijing
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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)
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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
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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
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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
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Comparison to TheoryComparison to Theory
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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
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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
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++ observations observations
u
du
12
12
K n configuration
dn
K+
u
du
12
12
diquark – triquark configuration of the uudds pentaquark
d
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ppppdKdK++KK00
non-resonant resonantV. Yu. Grishina, EPJ
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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 !
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dpdp33He He Q=28 MeV
p-wave!
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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
_
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and and ’ Production’ Production
phase space
+ pp fsi
+p fsi
3P01S0s
3P01S0s
+ 1S03P0s
+ 1D23P2s
importance of N* N+production!
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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
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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
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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
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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
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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
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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
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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)
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resultresult m = 547.257 0.044 MeV/c2
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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!
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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
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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
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SummarySummary
•COSY has unique beam properties: emittance, resolution, polarization
•Instruments are complementally to each other: acceptance, resolution
•Convincing physics program