Strangeness Production in p+A Interactions at 920 GeV.
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Strangeness Production in p+A Interactions at 920 Strangeness Production in p+A Interactions at 920 GeV. GeV. for the HERA-B collaboration Beam 920 GeV/c protons Acceptance – 15-160(v) resp. 250(h) mrad High mass resolution spectrometer Good particle identification Subdetectors used in the present study: • Silicon vertex detector (SVD) • Tracker (OTR) • RICH and mostly at mid rapidity (x F -0.15 – +0.05) The HERA-B Experiment at DESY Feature : works in the beam halo Advantage : different target materials may be used • Targets: • 1 kHz data acquisition rate. • Minimum bias trigger • 0.1 interaction per bunch crossing Signal per Target - C : Ti : W - 1 : 0.4: 2.2 V 0 p - Beam p A π Δz /γ Λ Λ 3414.6 +/- 2.3 k K 0 S 705.3 +/- 1.1 k 338.7 +/- 0.8 k Statistics (this analysis) : 0 V p p l p l p t p Signal per Target - C :Ti : W - 1 : 0.3 : 1.9 Statistics (this analysis): Ω + Ξ - Ω - Ξ + 4778 ± 78 3098 ± 63 444 ± 35 378 ± 27 t p (GeV/c) l p l p l p l p V 0 Beam p A π(K) Δz /γ π Ξ(Ω) p(p ) Carbon 76.6 10 6 Titanium 24.1 10 6 Tungsten 71.6 10 6 Interactions at: : Statistics (final): K + π - 533.2 ± 3.2 k K - π + 410.9 ± 3.0 k Signal per Target: C : Ti : W 1. : 0.4 : 1.4 K + K - 52.6 ± 0.4 k Signal per Target: C : Ti : W 1. : 0.5 : 1.7 Selecti and * K The V 0 selection. The Cascade Hyperons Selection. The particle ratios. HERA-B √s = 41.6GeV The particle ratios measured by the four RHIC collaborations, the statistical model and the HERA-B result (preliminary). The Differential p 2 t spectra σ p [GeV ] 2 t 2 Fit function: dσ /dp t 2 ∞ (1+p t 2 /p 0 2 ) -β valid for the whole p t 2 range β : changes for K* from 3.8 to 4.7 for Φ from 3.8 to 4.2 for C:Ti:W targets < p t > : changes from 0.64 to 0.73 for C:Ti:W targets and for all particles Observation of Cronin effect. For each bin, the spectra were fit to the formula: dσ pA /dp 2 t = A α dσ pp /dp 2 t The spectra are enhanced at high p 2 t may be due to multiple scattering inside the nucleus may be ….. B d σ / dp 2 t ∞ exp(-Bp 2 t ) The spectra follow a simple exponential law up to nearly 1. GeV/c: and becomes flatter at higher p 2 t . K 0 S 3.0 +/- 0.1 Ω + 1.7 +/- 0.8 Λ 2.2 +/- 0.1 Λ 2.2 +/- 0.1 Ξ - 1.8 +/- 0.2 Ξ + 1.8 +/- 0.2 Ω - 1.7 +/- 0.6 B - HERA-B preliminary • A thermal model predicts an opposite curvature resp. to the experimental curve. • The average <p 2 t > increases with the increase of the mass. K 0 * Presented by Marko Staric ( [email protected] ) 0 S K Experiment Thermal Model We observed : ) ( ) ( K , for all measured p t ) ( 9 . 0 ) ( 0 * K K , for all measured p t
description
p(p). V 0. Beam p. π ( K ). Ξ ( Ω ). A. π. Δ z / γ. 2. 2. p. p [GeV ]. HERA-B. K 0 S. 3414.6 +/- 2.3 k. t. √ s = 41.6GeV. V 0. -. π. Beam p. Beam 920 GeV/ c protons. Subdetectors used in the present study:. The HERA-B Experiment at DESY. A. - PowerPoint PPT Presentation
Transcript of Strangeness Production in p+A Interactions at 920 GeV.
Strangeness Production in p+A Interactions at 920 GeV.Strangeness Production in p+A Interactions at 920 GeV.for the HERA-B collaboration
Beam 920 GeV/c protons
Acceptance – 15-160(v) resp. 250(h) mrad
High mass resolution spectrometer
Good particle identification
Subdetectors used in the presentstudy:
• Silicon vertex detector (SVD)• Tracker (OTR)• RICH
and mostly at mid rapidity (xF -0.15 – +0.05)
The HERA-B Experiment at DESY
Feature : works in the beam halo
Advantage : different target materials may be used
• Targets:
• 1 kHz data acquisition rate.
• Minimum bias trigger• 0.1 interaction per bunch crossing
Signal per Target - C : Ti : W - 1 : 0.4: 2.2
V0
p
-Beam p
A
π
Δz /γ
Λ
Λ
3414.6 +/- 2.3 kK0S
705.3 +/- 1.1 k
338.7 +/- 0.8 k
Statistics (this analysis) :
0V
p
p
lp
lp
tp
Signal per Target - C :Ti : W - 1 : 0.3 : 1.9
Statistics (this analysis):
Ω +
Ξ-
Ω-
Ξ +
4778 ± 78
3098 ± 63
444 ± 35
378 ± 27
tp(G
eV/c
)
lp
lplp
lp
V0
Beam p
A
π(K)
Δz /γ
π
Ξ(Ω)
p(p)
Carbon 76.6 106
Titanium 24.1 106
Tungsten 71.6 106
Interactions at: :
Statistics (final):
K+π- 533.2 ± 3.2 kK-π+ 410.9 ± 3.0 kSignal per Target: C : Ti : W 1. : 0.4 : 1.4
K+K- 52.6 ± 0.4 kSignal per Target: C : Ti : W 1. : 0.5 : 1.7
Selectionand* K
The V0 selection.
The Cascade Hyperons Selection.
The particle ratios.
HERA-B
√s = 41.6GeV
The particle ratios measured by the four RHIC collaborations, the statistical model and
the HERA-B result (preliminary).
The Differential p2t spectra
σ
p [GeV ]2
t
2
Fit function: dσ /dpt2 ∞ (1+pt
2/p02)-β
valid for the whole pt2 range
β : changes for K* from 3.8 to 4.7 for Φ from 3.8 to 4.2 for C:Ti:W targets
< pt> : changes from 0.64 to 0.73 for C:Ti:W targets and for all particles
Observation of Cronin effect.
For each bin, the spectra were fit to the formula: dσpA /dp2t = Aα dσpp /dp2
t
The spectra are enhanced at high p2t may be due to multiple scattering
inside the nucleus may be …..
B
d σ / dp2t ∞ exp(-Bp2
t)
The spectra follow a simpleexponential law up to nearly 1. GeV/c:
and becomes flatter at higher p2t.
K0S 3.0 +/- 0.1
Ω+
1.7 +/- 0.8
Λ
2.2 +/- 0.1
Λ 2.2 +/- 0.1
Ξ- 1.8 +/- 0.2
Ξ +
1.8 +/- 0.2
Ω- 1.7 +/- 0.6
B
- HERA-B preliminary
• A thermal model predicts an opposite curvature resp. to the experimental curve.• The average <p2
t> increases with the increase of the mass.
K0*
Presented by Marko Staric ( [email protected] )
0SK
Experiment
Thermal Model
We observed :
)()( K , for all measured p t
)(9.0)( 0* KK , for all measured p t
![R in Low Energy e e [Ecm 5 GeV] · Table 1. R(Ecm≲5 GeV) from different laboratories Place Ring Detector Ecm(GeV) ptsYear Beijing BEPC BESII 2.0-5.0 1061998 -1999 Novosibirsk VEPP-2M](https://static.fdocument.org/doc/165x107/5f7c79d3af794e434822d967/r-in-low-energy-e-e-ecm-5-gev-table-1-recma5-gev-from-different-laboratories.jpg)
