Strangeness production around threshold region and

Strangeness production
around threshold region
and
a possibility with
the new beam line and NKS2
Masashi KANETA
for the NKS2 collaboration
Department of Physics, Tohoku Univ.
[email protected]
Outlook of this talk
• Introduction of the experiment
– Motivation
– Collaboration list
– Fruits of our study
• Physics topics
– strangeness production
– model and data
• Experiment with Neutral Kaon Spectrometer (NKS)
– setup
– results
• New spectrometer (NKS2)
• A possibility with new beam line and NKS2
Masashi Kaneta, Tohoku Univ.
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Introduction
Masashi Kaneta, Tohoku Univ.
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NKS experiment
• Focusing on strangeness production by
Electromagnetic interaction
– by g+p and g+n reaction
– using photon beam at Laboratory of Nuclear Science (LNS)-Tohoku
• 0.8-1.1 GeV (accuracy: 6MeV) g beam
from 1.2 GeV (2mA) electron
– information for
• meson-baryon interaction
• hadron structure
• What are our characteristics?
– measurement of neutral kaon
• K+ photo-/electro-production existed on markets in 1990’s
– Bonn-SAPHIR, Jlab-CLAS, SPring8-LEPS
• however no K0 data on the neutron target
• Studied with g+C and g+d reaction
– now under constructing a new spectrometer (NKS2)
Masashi Kaneta, Tohoku Univ.
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Collaborators are:
• Department of Physics, Tohoku University
– K. Tsukada, M. Ejima, Y. Fujii, O. Hashimoto, K. Hirose,
Hutatsugawa, S. Kameoka, H. Kanda, M. Kaneta, D. Kawama,
Katoh, S. Kinoshita, T. Kon, K. Maeda, N. Maruyama,
Matsumura, Y. Miura, Y. Miyagi, H. Miyasei, S.N. Nakamura,
Nomura, K. Nonaka, A. Ohtani, Y. Okayasu, M. Oyamada,
Shirotori, T. Takahashi, H. Tamura, H. Tsubota, D. Uchida,
Ukai, H. Yamauchi, K. Yawata, M. Wakamatsu, T. Watanabe
K.
H.
A.
H.
K.
M.
• Laboratory of Nuclear Science, Tohoku University
– T. Ishikawa, T. Kinoshita, H. Miyahara, T. Nakabayashi,
Shimizu, T. Tamae, T. Terasawa, H. Yamazaki
H.
• Department of Electrical and Electric Engineering, Akita University
– A. Sasaki
• Department of Electrical Engineering, Ichinoseki National College of
Technology
– O. Konno
Masashi Kaneta, Tohoku Univ.
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Fruits of our study
• Thesis
– 2 of Dr. Sci. (T. Watanabe, K. Tsukada),
7 of M. Sci. and 4 of B. Sci. in 5 years
• Conference talk
– PANIC02
• Photoproduction of Neutral Kaons on C in the Threshold Region
– LEPS03
• K0 and double pion photoproduction experiments at LNS
– SENDAI03
• Photoproduction of Neutral Kaons in the Threshold Region at LNS
– HYP2003
• K0 photoproduction on
– Hirschegg 2004
12C
in the threshold region
• Photoproduction of neutral kaons on carbon and liquid deuterium
targets in the threshold region
• JPS talk
– 15 talks in 2001-2005
• Publication
– now on going.....
Masashi Kaneta, Tohoku Univ.
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Physics topics
Masashi Kaneta, Tohoku Univ.
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Strangeness photo-production
Masashi Kaneta, Tohoku Univ.
stealing from Kyo TSUKADA’s defense talk with respect
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Strangeness photo-production
Solid lines:
theoretical
calculation
by KaonMAID
Masashi Kaneta, Tohoku Univ.
stealing from Kyo TSUKADA’s defense talk with respect
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Strangeness photo-production
Masashi Kaneta, Tohoku Univ.
stealing from Kyo TSUKADA’s defense talk with respect
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Strangeness photo-production
Masashi Kaneta, Tohoku Univ.
stealing from Kyo TSUKADA’s defense talk with respect
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Strangeness photo-production
Masashi Kaneta, Tohoku Univ.
stealing from Kyo TSUKADA’s defense talk with respect
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Strangeness photo-production
Masashi Kaneta, Tohoku Univ.
stealing from Kyo TSUKADA’s defense talk with respect
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Strangeness photo-production
Masashi Kaneta, Tohoku Univ.
stealing from Kyo TSUKADA’s defense talk with respect
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Experimental
setup of NKS
Masashi Kaneta, Tohoku Univ.
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LNS STB ring and NKS
• Conditions at this
experiment
– Eg : 0.8-1.1 GeV (Eth=0.91)
– Duty factor : ~ 60 %
– Beam current : ~ 2 mA
Masashi Kaneta, Tohoku Univ.
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The spectrometer
K0S g p+ pB.R. ~ 68.6 %
ct ~ 2.67 cm
• TAGX magnet
– Dipole magnet with 0.5 T
• Inner Hodoscope (IH) and
Outer Hodoscope (OH)
– Trigger counter
– Time of flight measurement
• CDC (cylindrical drift chamber) and
SDC (straw drift chamber)
– Tracking
– Momentum
• EV (electron veto counter)
– e+e- background suppression
Masashi Kaneta, Tohoku Univ.
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Results from
NKS experiment
g+C(n)  K0+X()
g+d(n)  K0+X()
Masashi Kaneta, Tohoku Univ.
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Results of NKS experiment
• g+C(n)  K0+X()
fromTakaomi Watanabe’s Dr. Thesis
K0: NKS
(0.800 < cosq < 1.000)
K+: H.Yamazaki et al. (0.766 < cosq < 0.985)
Phys. Rev. C51 (1995) R1074
Integrated region: almost same
acceptance effect
K0: uncorrected (<5%)
K+: corrected
 C (g , K 0)
 1.1  0.1
 C (g , K + )
K0 cross section is close to K+ one
Masashi Kaneta, Tohoku Univ.
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Results of NKS experiment
• g+C(n)  K0+X()
– K0 Cross section as a function of
momentum, cosq (= pZ/p), and Eg
from Takaomi Watanabe’s Dr. Thesis
Masashi Kaneta, Tohoku Univ.
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Results of NKS experimentg+C(n)  K +X()
0
• The model has:
– same order of
magnitude for cross
section
– underestimate in
low Eg and p region
• need a correction
of the model for K0
 channel
stealing from Takaomi Watanabe’s defense talk with respect
Masashi Kaneta, Tohoku Univ.
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Results of NKS experimentg+C(n)  K +X()
0
rKK1 = g(K10 K0 g) /g(K1+ K+ g)
when Kaon-MAID value is used for rKK1,
SLA model do not represent the data
With rKK1= -1.4 - -1.8
good agreement with the data
stealing from Takaomi Watanabe’s defense talk with respect
Masashi Kaneta, Tohoku Univ.
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Results of NKS experiment g+d(n)  K +X()
0
stealing from Takaomi Watanabe’s defense talk with respect
Masashi Kaneta, Tohoku Univ.
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Results of NKS experiment g+d(n)  K +X()
0
}
background
estimated
1: pp pair from
out of target
(r, w, etc)
2: accidental
coincidence
of p from K0
and p from 
stealing from Takaomi Watanabe’s defense talk with respect
Masashi Kaneta, Tohoku Univ.
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Results of NKS experiment g+d(n)  K +X()
0
stealing from Takaomi Watanabe’s defense talk with respect
Masashi Kaneta, Tohoku Univ.
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Summary of the NKS experiment
• Neutral kaon production by g+n  K0+ is studied via
– g+C  K0+X() and g+d  K0+X() reaction
• First time measurement of K0 cross section in g+d
• Comparison of data with two models
– Kaon-MAID
• in g+C
– seems to underestimate in low momentum (backward direction)
• in both g+d and g+C
– SLA
– over estimate in p>0.7GeV/c and Eg =1.0 – 1.1 GeV
• with tuning of the free parameter rKK1
– rKK1=-1.4 to -1.8 for g+C data
– rKK1~
- -2.0 for g+d data
• Need more statistics to conclude rKK1
– additionally, need to consider a nucleus effect in C
• We expect more statistics with NKS2
– 2 times of K0 and 10 times of  compared with NKS
Masashi Kaneta, Tohoku Univ.
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The new
spectrometer
NKS2
Masashi Kaneta, Tohoku Univ.
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The new spectrometer (NKS2)
• New magnet
(so called 680 magnet)
– used for cyclotron in CYRIC-Tohoku
– 0.42T (1000A, 110V)
• New cylindrical drift chamber
– covered forward region
680 magnet
view from downstream
Masashi Kaneta, Tohoku Univ.
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Comparison of new CDC with old one
•New CDC
–covered forward
region
–3D tracking by x,u,v
wire read-out
–acceptance
• 20–80 cm radius
• 165 deg in zx plane
along the beam
• 165cm height
• 1.127 p Sr (28.18%
of total solid angle)
Masashi Kaneta, Tohoku Univ.
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Some pictures of NKS2
680 magnet
STB ring
Detectors will be installed
from this autumn
Masashi Kaneta, Tohoku Univ.
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A possibility with
the new beam line
and NKS2
Masashi Kaneta, Tohoku Univ.
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A possibility(-ies)
• It is just rough idea which MK hit upon....
– that is, might be “Picture of Rice cakes (= “Pie in the sky”)
Masashi Kaneta, Tohoku Univ.
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A possibility(-ies)
• With large acceptance of 680 Magnet
+ CDC + a
– Strangeness production study
• , *,.. (also polarization measurement)
– many resonances will be backgrounds
• multi-strangeness baryons are interesting
– need inner tracker (Mini TPC, Si detector, etc.)
• charmonium??
– cross section/polarization measurement
– with several Eg, if possible
– Sea quark (ss) contribution in spin structure of
nucleons
• an asymmetry of
Masashi Kaneta, Tohoku Univ.
 production with polarized g beam
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Summary
Masashi Kaneta, Tohoku Univ.
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Summary
• Neutral kaon production by g+nK0+ is studied via
– g+C  K0+ and g+d  K0+ reaction
• First time measurement of K0 cross section in g+d
• Comparison of data with two models
– SLA show better agreement than Kaon-MAID
• however, it is not perfect
• to fix a free parameter rKK1, need more statistics
• We expect more statistics with NKS2
– 2 times of K0 and 10 times of  compared with NKS
• Some rough ideas for new beam line with NKS2 are
presented
Masashi Kaneta, Tohoku Univ.
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Backup
Masashi Kaneta, Tohoku Univ.
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新旧スペクトロメータの比較アクセプタンス
NKS
新スペクトロメータ
0.90 GeV < Eγ < 0.95 GeV
cosθlab
cosθlab
0.90 GeV < Eγ < 0.95 GeV
K0
K0 momentum (GeV)
momentum (GeV)
Color :
Acceptance
Solid line :
Kaon-MAID
1.05 GeV < Eγ < 1.10 GeV
K0 momentum (GeV)
D2
K0 生成断面積
cosθlab
cosθlab
1.05 GeV < Eγ < 1.10 GeV
K0 momentum (GeV)
ほぼ全運動学的領域を覆っている。
K0で2倍、Λで10倍の収量が期待できる。
Masashi Kaneta, Tohoku Univ.
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By ( T )
新旧スペクトロメータの比較電磁石
0.5
TAGX magnet
680 magnet
0.4
0.3
0.2
0 .1
0
0
200 400 600 800 1000 1200
R dir. ( mm )
旧スペクトロメータ (NKS)
TAGX magnet
新スペクトロメータ
680 magnet
磁極半径
535 mm
800 mm
ギャップ
600 mm
680 mm
重量
30 t
120 t
電流
500 A
1000 A
最大平均磁場
0.5 T
0.4 T (TOSCA simulation)
Masashi Kaneta, Tohoku Univ.
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