baryon spectroscopy with ( ,2 reactions at j-parc e45 · 4/13/2015 · hiroyuki sako asrc/j-parc,...
TRANSCRIPT
Hiroyuki Sako
ASRC/J-PARC, JAEA
for J-PARC E45 Collaboration
PWA8/ATHOS3, 13 Apr 2015, GWU
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Baryon spectroscopy with (p,2p) reactions at J-PARC E45
11/21/2014
1. Physics motivation
2. J-PARC E45
3. Detector status
5. Summary
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J-PARC E45 Studies of baryon resonances in (p,2p) reactions for
• Precise measurements of baryon resonance properties – Many resonances have not been established experimentally
– ppN has strong coupling to high mass resonances
– Not enough (p,2p) experimental data since 1970’s
• Deeper understanding of non-perturbative QCD
• Search for new baryon states – e.g. hybrid baryons (qqqg)
p
N
N*
p p
N
3 PDG 2014
Baryon mass: Exp vs QM (PDG)
Missing baryons Quark model does not describe well N* mass levels.
Orders of mass levels
are different
* ** ***
****
Most of the N*s so far were
Measured from
established
Partial wave (LSJ) amplitude of a b reaction:
Reaction channels:
Transition potentials:
coupled-channels effect
Dynamical coupled-channels model (ANL-Osaka)
exchange potentials
of ground state
mesons and baryons bare N* states
For details see Matsuyama, Sato, Lee, Phys. Rep. 439,193 (2007) Kamano’s talk (Apr 14)
core
meson cloud
meson
baryon
Physical N*s will be a “mixture” of the two pictures:
2012 May 18 4 JAEA Seminar
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Importance of Npp Decay H. Kamano, et al. PRC 79 025206 (2009)
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World’s pN→ppN data Only 240K bubble chamber data in 1970’s
H. Kamano et al., PRC 79, 025206 (2009).
No channel
coupling
With channel
coupling
ppN center of mass energy
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Recent Lattice QCD calculations N
ote
: N
ot
real m
ass!
J. Dudek et al., PRD85 (2012) 054016
Hybrid baryons
(qqqg)
N(939)
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Bird’s eye photo in January of 2008
Neutrino Beams (T2K experiment)
Hadron Exp. Facility
Materials and Life Experimental Facility
3 GeV Synchrotron
400 MeV LINAC
J-PARC (MW proton synchrotron)
Hadron Experimental Facility
L,X N
Z L, S Hypernuclei
LL, X Hypernuclei
Str
an
ge
ne
ss
0
Hypernuclei
-1
-2
K1.8
KL
SKS
K1.8BR K1.1
d
u u
d
s
Pentaquark + LLHe 6
Free quarks Bound quarks
Why are bound quarks heavier?
Quark
Vector meson in nucleus Kaonic nucleus
Implantation of
Kaon and the
nuclear shrinkage
K meson
2014/03/17 9 J-PARC HI WS, K. Ozawa
E16
1014/cycle p beams
108/cycle p beams
106/cycle K beams
(2017) cycle ~ 6s
Measure (p,2p) in large acceptance TPC in dipole magnetic field p-p→p+p-n, p0p-p 2 charged particles + 1 neutral particle
p+p→p0p+p, p+p+n →missing mass technique
pN→KY (2-body reaction)
p-p→K0L,
p+p→K+S+ (I=3/2, D*)
p+- beam on liquid-H target
(p= 0.73 – 2.0 GeV/c
W=1.5-2.15 GeV) LH target
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E45 HypTPC Spectrometer
Hyp-TPC Superconducting Helmholtz
Dipole magnet
Trigger with hodoscope
p beam
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HypTPC Large acceptance
H-target inside TPC
High-rate capable TPC
Gating Grid
GEM(Gas Electron Multiplier)
Suppression of positive-ion backflow causing position distortions
Good position resolution with magnetic field and fine-segmented pads
p/K/p separation
dE/dx vs p
p- beam ~
55
0
Gating grid wires GEM (e amplification)
Pad plane
Target holder
500φ 70φ
B=1.5T
E=180V/cm
P-10 gas
Liquid H target
ionization
Electron
drift
p-
p+
n e-
Gas vessel
Field cage (sensitive volume)
544
544
130
Target
position
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GEM (Gas Electron Multiplier)
・4 GEM (250mmx250mm) sheets
・3-GEM layers
50mm + 50mm +100mm thick
Gain ~ 104
Segmented electrodes
・to reduce spark rate / electrode
・to minimize acceptance loss
when an electrode is broken due
to discharge
Hit distribution (GEANT)
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Readout pad configuration
Pad size
2.4 x 9 mm2 (inner layer)
2.4 x 13 mm2 (outer layer)
32 pad rows (rings)
No. of pads = 5768 520
215
52
0
Position resolution <300mm
(L>10cm)
Dp/p=1-3% (p,p)
Detector simulation (GEANT)
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3-body reaction
MM2(π±p)
Elastic scattering (Same trigger condition)
Cut on coplanarity cut. Only 3-body reaction can
be survived.
Rejected events by coplanarity cut
p-p → p- p0p reaction
p- p-
p
coplanarity
=cosine of angle
Between p1 and
(p2xp3)
p1
p2
p3
Particle identification
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p-
p+
p
K+
p- p+ K+
p
p/K : p<=0.5 GeV/c
p/p : p<=1.1 GeV/c
w/ Hodoscope TOF
sT = 100ps
Trigger efficiency
Proposed
hodoscope with 32
segments.
80 cm
2-charged particle trigger
(inefficiency due to double hit)
Acceptance
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Momentum of Proton > 300 MeV/c (large energy loss in target)
p+p → p+p0p reaction
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Data statistics ・ (p,2p) cross section : ~2 mb
・p Beam rate : ~106 / cycle (6s)
・Liquid H target : 5cm length
・TPC acceptance : 40%
160 events / cycle
Dominant background: elastic scattering
(stotal= 40 mb trigger rate = 3200 events / cycle
~ 800 Hz in maximum (4s flat top))
・Energy range : 1.50 – 2.15 GeV
・No. of bins : p- beam : 24 (energy) x 20 (angle)
p+ beam : 23 (energy) x 20 (angle)
・No. of events / bin : 32 K
30M events in 15 days
Increase world’s ppN data (240K) by factor of 130
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TPC prototype test NIMA763(2014)65-81
• Beam test at RCNP – Proton beam at 400 MeV
– Beam rate up to 106 Hz /cm2
Hit position distortion <0.1mm
Efficiency vs rate
3m
TPC
SSD
Proton
beam
Position resolution (B=0) sx=0.40mm (4mm pad)
Ion backflow ~ 5% (bench test)
HypTPC test
r-CoBo
(data collector)
GET(General Electronics for TPC)
readout system
HypTPC
10cm
70cm AsAd(amplifier/ADC)
Mar 2015
HypTPC test
with 55Fe (x-ray) source
ΔE/E :14.3 ± 0.2 %
5.9 keV peak 2.7 keV peak
Gain : 120fC, Shap T: 70ns, GEM Curr.: 315 mA
(Peak)/(Esp. Peak): 0.52 ± 0.01 Diffusion size : 1.87 ± 0.02 mm
cf. prototype TPC(5 cm to 10 cm) : 1.7 ~ 2.0 mm
The TPC operation is consistent with the prototype TPC!!
Physics possibilities with HypTPC
• H-dibaryon (E42) : K-CK+H X, HLL,Lp-p
• L(1405) : p-pK0L(1405)
L(1405)Lg (KN compositeness, T. Sekihara, PRC89 (2014) 025202)
• K-pp : p+dK+K-pp
K-ppLp,S0p,Lp0p,S0p0p
• X excited states: K-p K+X-*, X-* LK-, S0K-, S-K0, X-p0, X0p-, X-g
K-p K0X0*, X0* LK0, S0K0, S+K-, X-p+
• X-C atom (E42) :K-CK+X-X, X- capture in C
X-ray detection in TPC (Ar gas)
• pNphN
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Summary • J-PARC-E45 is proposed to study baryon excited
states in (p,2p) reactions, which will improve previous data statistics by two orders of magnitude.
• Large acceptance TPC in high rate operation will realize the experiment.
• E45 spectrometer will be ready for beams in 2016 with the TPC and the magnet.
• PWA with dynamical coupled channels model in collaboration with theorists (H. Kamano, T. Sato,..)
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E45 collaboration list
K. H. Hicks, S. Chandavar, J. Goetz, W. Tang (Ohio University, USA)
H. Sako, K. Imai, S. Hasegawa, S. Sato, K. Shirotori, S.H. Hwang (Japan Atomic Energy Agency, Japan)
S.H. Kim, S.J. Kim, S.Y. Kim, A. Hi, J.Y. Park, S.Y.Ryu (Pusan National University, Korea)
J.K. Ahn (Korea University, Korea)
H. Fujioka, S. Nakamura, M. Niiyama (Kyoto University, Japan)
K. Ozawa (KEK, Japan)
B. Bassalleck, Y. Han (University of New Mexico, USA)
K. Joo, N. Markov, N. Harrison, T. O’Connell, E. Seder (University of Connecticut, USA)
B. Briscoe, F. Klein, I. Strakovsky, R. Workman (George Washington University, USA)
R. Schumacher (Carnegie Melon University, USA)
D. M. Manley (Kent State University, USA)
L. Guo (Florida International University, USA)
P. Cole , A. Forest, D. McNulty (Idaho State University, USA)
T.S.-H. Lee (Argonne National Lab, USA)
T. Sato, H. Kamano (Osaka University, Japan)
Y. Azimov (Petersburg Nuclear Physics Institute,Russia)
V. Shklyar (University of Giessen, Germany)
A. Svarc (Ruder Boskovic Institute, Hungary)
S. Ceci (RBI-Zagreb, Hungary)
M. Hadzimehmedovic, H. Osmanovic (University of Tulza, Bosnia/Herzegovina)
46 people form USA, Japan, Korea, and Europe