Transcript J-PARC Japan Proton Accelerator Research Complex

Hadron Physics at J-PARC
Shin’ya Sawada
澤田 真也
KEK
(High Energy Accelerator Research Organization, Japan)
AFTER@LHC, ECT*, Feb. 5. 2013
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Contents
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Overview of J-PARC and Hadron Experimental
Facility (Hadron Hall)
Physics with Low Momentum Secondary Beams
Physics with High-Momentum Beams
Extension
Summary
2
Goals at J-PARC
Need to have high-power
proton beams
 MW-class proton accelerator
(current frontier is about 0.1 MW)
Materials & Life Sciences at 3 GeV
Nuclear & Particle Physics at 50 GeV
R&D toward Transmutation at 0.6 GeV
3
Location of J-PARC at Tokai
KAMIOKA
295 km
JAEA
JAERI
1 hour
Tokai
J-PARC
KEK
Tsukuba
TOKYO
NARITA
4
Linac
3 GeV
Synchrotron
Neutrino Beams
(to Kamioka)
J-PARC Facility
(KEK/JAEA）
South to North
Experimental
Areas
Materials and Life
Experimental Facility
JFY2007 Beams
JFY2008 Beams
JFY2009 Beams
Hadron Exp.
Facility 5
Bird’s eye photo in January of 2008
Hadron Experimental Facility (Current Layout)
Ｔ１ Target
(30/50% Loss)
50GeV Synchrotron
SM1
(2% Loss)
50GeV Tunnel
T0
0.1% Loss)
Extension
Test BL
Hi-P BL
Switchyard
Hadron Hall
Beam Dump
6
n
X hypernuclei
experiments
in Hadron Hall
L
Kp
p
K1.8BR
K-pp bound states
Production
K- atomic
X rays
target (T1)
h mesonic nuclei
30~50 GeV
primary beam
p
LL hypernuclei
X-atomic X-rays
L hypernuclear g rays
Neutron-rich L hypern.
Pentaquark Q+ search
K-pp bound state
Hyp. weak decay(A=4)
Hyp. weak decay(A=12)
p Double charge exch.
w mesonic nuclei
Sp Beam
scattering
Dump
K1.8
K0
L
Slide By
H.Tamura
rare decays
Hadron mass in nuclei
Nucleon quark structure
KL
K1.1
High momentum line
Not constructed
yet nuclei
F mesonic
K1.1BR
T violation in K+ decay
Universality in K+ decay
Q+ study by K+n scattering
Approved (stage-2) / (stage-1) / proposed,LOI
L hypernuclear g rays
S-nuclear systems
YN scatering
Q+ hypernuclei
m-e conversion search7
7
Season of Fruits at Hadron Hall Comes!
Beam Intensity is being upgraded.
Contents





Overview of J-PARC and Hadron Experimental
Facility (Hadron Hall)
Physics with Low Momentum Secondary Beams
Physics with High-Momentum Beams
Extension
Summary
9
Physics with Low Momentum Secondary Beams


So far there are only low-momentum beam lines.
Strangeness nuclear physics
– With (pi, K), (K, pi), and (K-, K+) reactions

Other hadron physics
– Many strangeness related, but a few non-strange.

Low Momentum Secondary Beams
– Pions and Kaons <2 GeV/c at K1.8 beam line
• Momentum was selected so that the production cross section of the Xsi
baryon is at the maximum.
• Major goal is S=-2 hypernuclei (Xsi nuclei and double-Lambda nuclei).
• Used also for (pi, K) reaction for single hypernuclei.
– Pions and Kaons <1.1GeV/c at K1.8BR and K1.1 beam line
• Single Lambda hypernuclei
• Gamma ray spectroscopy
• Search for K-pp bound states
10
Three Dimensional Nuclear Chart
Nu ~ Nd ~ Ns
Strange hadronic matter (A → ∞)
Strangeness
“Stable”
Strangeness in neutron stars ( r > 3 - 4 r0 )
Higher
density
LL, X Hypernuclei
Z
-2
L, S Hypernuclei
N
-1
0
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Single strangeness experiments





E19 (published): Pentaquark search
E10 (took data): Neutron-rich hypernuclei with
double-charge exchange
E13 (coming soon): Gamma ray spectroscopy of
hypernuclei
E15 (took some data): Search for K-+p+p bound state
… (many waiting)
12
E19: Pentaquark Search





search for Θ+ in p(π– , K–)
target : liquid H2, 0.86g/cm2
at K1.8 beamline + SKS
beam momentum :
–
pπ=(1.87,1.92,2.00GeV/c)
4.8 x 1011 p on target for each pπ


beam intensity : 107/spill(2sec.)
beam time : 160 hours
Yield : 104 events for each momentum
Sensitivity : 75nb/sr
 confirm the existence of Θ+
E19 took the first physics data
with p=1.92 GeV/c in Oct/Nov,
2010, and p=2.0 GeV/c in Feb,
2012.
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SKS: ideal for Θ+ detection
large acceptance : 0.1sr
ΔM = 2.5MeV FWHM
E19: Pentaquark Search
14
Study on 6ΛH hypernucleus by
the (π-,K+) reaction at J-PARC
Hitoshi Sugimura
Kyoto University/JAEA
For J-PARC E10 Collaboration
6/6/2013
International Nuclear Physics Conference 2013
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J-PARC E10 experiment
L-hypernuclei
N~Z (I=0 or 1/2)
Non Charge-Exchange (NCX)
( K  , p  ) (p  , K  )
ordinary nuclei
N>>Z
or 2)
hyperfragments
by emulsions exp.(I=3/2
( K  , p  ) (p  , K  )
π-+p+p->K++n+Λ
Double Charge-Exchange (DCX)
J-PARC E10
6/6/2013
International Nuclear Physics Conference 2013
16
6
ΛH
production by FINUDA
• 6Li(stopped K-,π+) reaction
M. Agnello et al., FINUDA Collaboration, PRL 108 (2012) 042501
• Measured formation and weak
decay in coincidence
K   6Li  p   L6H
H  p   6He
• cut on T(π+)+T(π-)
6
L
• 3 events of candidates
6/6/2013
International Nuclear Physics Conference 2013
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Experimental Setup
LC SDC4
SDC3
•K1.8 Beamline
-1.2GeV/c π- Beam
Δp/p ~3.3x10-4
Momentum is measured by the
Transfer Matrix
BFT(x)-BC3,4(x,y,x’,y’)
AC
•SKS Spectrometer
Central Momentum 0.9GeV/c
Δp/p~1.0x10-3
Momentum is calculated or estimated
Runge-Kutta method
SFT,SDC2(x,y,x’,y’)-SDC3,4(x,y,x’,y’)
Scattered Kaon identified TOFxLCxAC in
online trigger
6/6/2013
GC BFT
BH1
International Nuclear Physics Conference 2013
TOF
BH2
SKS
+
K
SDC2
SFT
BC4SSD
BC3
π
J-PARC
K1.8 Beam Line
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Calibration Runs
•Results of analysis
p(π-,K+)Σ-
+1.20GeV/c 12C(π+,K+)12ΛC
- 1.37GeV/c p(π-,K+)Σ+1.37GeV/c p(π+,K+)Σ+
12C(π+,K+)12
ΛC
Ex(pΛ)
ΔBΛ:2.8MeV/c2
(FWHM)
ΔM:2.5MeV/c2
(FWHM)
Measure:1200.39MeV
PDG:
1197.45MeV
Yield :
~6000events
p(π+,K+)Σ+
ΔM:2.6MeV/c2
(FWHM)
g.s.(sΛ)
Measure: 1188.41MeV
PDG:
1189.37MeV
Yield :
~2000 events
Λ-QF
6/6/2013
Yield (g.s):
~600events
Σ-QF
International Nuclear Physics Conference 2013
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Counts/MeV
Missing Mass
Λcontinuum
Missing Mass[GeV/c2]
Σcontinuum
Missing Mass[GeV/c2]
•Could measure not only Λ-continuum region but also Σ-continuum region.
•Back ground level is enough lower than Λ-continuum.
•According to simple extrapolation of Λ-continuum, we observed some excess
at the low mass region. But it is too early to conclude at this moment.
•Production cross section of 6ΛH is smaller than we expected (10nb/sr).
6/6/2013
International Nuclear Physics Conference 2013
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E13: Hypernuclear g Spectroscopy
High-precision (DE～3 keV FWHM) spectroscopy with Ge detectors
1. YN, YY interactions
Unified picture of B-B interactions
Understand short-range nuclear forces
Understand high density nuclear matter (n-star)
Level energies ->LN spin-dependent forces,
Charge symmetry breaking, SN-LN force,…
E13
2. Impurity effects in nuclear structure
Changes of size/shape, symmetry, cluster/shell structure,..
B(E2), E(2+) -> shrinking effect, deformation change
3. Medium effects of baryons probed by
hyperons
B(M1) -> mL in nucleus
E13
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Double-strangeness hypernuclei soon
in ~700 Ξstops
NAGARA event
+6 cand.
t
ΛΛ6
H
p
e
4
He
in ~80 Ξstops
PS-E373
Ξ-
PS-E176
e
5
ΛH
10
μm
for L6LHe
1.01±0.20 MeV
5
0
0
5
ΔBLL =
10

With the improvement of the proton beam intensity, double-strangess
experiments with (K-, K+) become possible soon.
E07: Systematic Study of Double Strangeness System with an EmulsionCounter Hybrid Method
π-

#1
Double-Hypernucleus
with sequential decay
surely exists.
A
X
S
#2 #1
Ξ
10
p
#3
#2
5
0
5 10
(mm)
22
B
Double-strangeness hypernuclei soon

E07: Systematic Study of Double Strangeness
System with an Emulsion-Counter Hybrid Method
– Physics
1) S=-2 nuclear chart by ~102 LLZ via 104 X --stopping
events.
=> DBLL of several nuclides will provide definitive
informationon LL interaction and structure of S=-2 nuclei.
2) H-dibaryon state in S=-2 system ?
=> measure A-dependence of DBLL & Sdecay mode of
LLZ.
3) X -nucleus potential
=> detection of twin hypernuclei
=> First measurement of X-ray of X -atom
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Contents





Overview of J-PARC and Hadron Experimental
Facility (Hadron Hall)
Physics with Low Momentum Secondary Beams
Physics with High-Momentum Beams
Extension
Summary
24
Physics with High-Momentum Beams


“High-momentum beam line” (+ COMET beam line)
has been funded!
High-momentum primary proton beam (30GeV)
– Meson mass modification inside nuclei
– Dilepton measurement for nucleon and baryon structure

High-momentum meson (pion) beam (~<15 GeV/c)
– Pion-induced Drell-Yan?
– Baryon spectroscopy with pion beams.
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High-p and COMET


New primary Proton Beam Line
= High-momentum BL + COMET BL
High-momentum Beam Line
– Primary protons (~1010 – 1012pps)
• E16 (phi meson) is considered to be the first experiment.
– Unseparated secondary particles (pi, …)
• High-resolution secondary beam by adding several quadrupole
and sextupole magnets.

COMET
–
–
–
–
Search for m to e conversion
8 GeV, 50 kW protons
Branch from the high-momentum BL
Annex building will be built at the south side.
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New Primary Proton Beam Line
Separation
High-p
COMET
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Mass modification of vector meson
qq
QCD Vaccum
r ,T
Spontaneous Breaking of
Chiral Symmetry
Restoration
Hot/Dense Matter
Vector meson mass
at normal nuclear density
m*/m=1-kr/r0
(Hatsuda&Lee PRC46(92)R34)
r/w : Dm = 130 MeV at r0
f : Dm = 20~40 MeV at r0
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Results of a previous experiment (KEK-PS E325):
Invariant mass spectra of f e+e1.25<bg<1.75
1.75<bg (Fast)
Large Nucleus
Small Nucleus
bg<1.25 (Slow)
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PRL 98(2007)042501
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J-PARC E16: Electron pair spectrometer
to explore the chiral symmetry in QCD
primary proton beam at high momentum beam line
+ large acceptance electron spectrometer
107 interaction (10 X E325)
1010 protons/spill
with 0.1% interaction length target
 GEM Tracker
eID : Gas Cherenkov
+ Lead Glass
Large Acceptance (5 X E325)
velocity dependence
nuclear number dependence (p  Pb)
centrality dependence
systematic study of mass modification
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Possible hadron exps at high-momentum BL

Sea quark structure through Drell-Yan measurement
– Currently the E906/SeaQuest is running at Fermilab with 120-GeV protons
to see d-bar/u-bar asymmetry.
– Larger x possible with 50-GeV protons at J-PARC.
• J-PARC is currently operated with 30-GeV and there are no demands of 50-GeV
operation from other experiments, which needs modification of a part of the
accelerator components.
– There could be other possibilities of physics with dimuon
measurement such as,
• J/Psi measurements to see the nucleon
sea,
• dimuons from pion/kaon induced
reactions to see meson-like
substructure of a nucleon.

Spin related quantities
–
–
–
Polarized beam relatively far future.
Polarized target would be available in the near future.
Measurement such as Bohr-Mulders can be carried out
even with unpol. Drell-Yan measurements.
J/Psi: gg or q-qbar?
E866data:  ( p  d  X ) / 2 ( p  p  X )
Lingyan Zhu et
al., PRL, 100
(2008) 062301
Drell-Yan:  pd / 2 pp  [1  d ( x) / u ( x)]/ 2
J / ,  :
 pd / 2 pp  [1  g n ( x) / g p ( x)]/ 2
Gluon distributions in proton and neutron are very similar at 800 GeV. At much
lower energies, J/Psi might be produced by q-qbar annihilation.  Azimuthal
angle dependence. If J/Psi production is q-qbar annihilation, J/Psi becomes a tool
33
to investigate quark structure of nucleon at lower energies.
Unseparated Secondary Beam Intensity
beam loss limit @ SM1:15kW
(limited by the thickness of the tunnel wall)
with 15kW beam loss
[GeV/c]
extraction angle：5° smaller angle possibility being investigated
Exclusive Pion-Induced Drell-Yan Process
small t  (q  q)
2
Bernard Pire , IWHS2011
large t  (q  q)2
g * (q)
fp : pion distritribution amplitude (DA)
•DA characterizes the minimal
valence Fock state of hadrons.
•DA of pion are also explored
by pion-photon transition form
factor in Belle and Barbar Exps.
TDA : p -N transistion distritribution amplitude
•TDA characterizes the nextto-minimal valence Fock state
of hadrons.
•TDA of pion-nucleon is
related to the pion cloud of
nucleons.
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Accident

Radiation accident occurred at Hadron Hall on May 23rd.
–
–
–
Due to a malfunction of the beam extraction system of the 50 GeV synchrotron, a
proton beam was delivered to the gold target of the Hadron facility within a very short
time (30GeV, 2E13protons in ~5ms). As a result, the gold target is considered to have
momentarily reached an extremely high temperature and a part of the target was
damaged. Radioactive material then leaked into the hadron experimental hall and
some workers were externally and/or internally exposed to radiation.
Operation of ventilation fans of the hall resulted in leak of radioactive material out of the
radiation controlled area of the Hadron Experimental Facility. The data logs of radiation
dose rates at monitoring posts at the border of the J-PARC site showed no signatures.
However, at three monitoring posts and stations of a neighboring JAEA facility,
momentary increases of the radiation dose rate were observed. It is assessed that the
released radioactive material was diluted and attenuated as it dispersed in a narrow
strip towards the west. The maximum integrated radiation dose has been estimated
even at the site boundary closest to the Hadron Experimental Facility was 0.29 µSv
(preliminary).
All the J-PARC facilities have been shutdown since the accident. A full investigation of
the cause of the accident is now underway along with the complete review of safety
practices and emergency procedures at all J-PARC facilities. Our first priority is to
restore public trust in the facility by developing and implementing measures to prevent
the reoccurrence of an accident and to provide a safe experimental environment for
users and workers.
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Summary

Physics experiments have started at the Hadron Hall of JPARC, and the first physics paper is being published from the
E19 experiment. So far experiments with lower momentum
pions/kaons are being carried out.

The funding for the high-momentum beam line with COMET has
been approved by the government. The construction is
expected to start soon. Mass shift of phi meson would be the
first experiment, and other experiments are being discussed.

J-PARC is now very busy to respond to the accident. We don’t
have any forecast on the schedule, but we make our best.
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