International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) Neutral kaon photoproduction at LNS,
Tohoku Masashi Kaneta for the NKS/NKS2 collaboration Department of
Physics Tohoku University
Slide 2
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) Introduction 2 Masashi Kaneta, Tohoku
Univ.
Slide 3
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) Physics Motivation Investigation of
strangeness production mechanism Threshold region of the production
No resonance decay effect Good for comparison with models Give
theoreticians base data to address Coupling constant Resonance
contribution Small cross-section, i.e. high statistics data is
required Neutral channel in the strangeness photo-production Past
experiments studied by K + production until 2002 Not enough data of
differential cross-section of +n K 0 + 3 Masashi Kaneta, Tohoku
Univ.
Slide 4
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) Model dependence in cross-section
Models are based on K + experimental data There is large model
dependence for K 0 cross-section Solid-White: Kaon-MAID Dash-Red:
Saclay-Lyon A (rkk=-0.45) 4 Masashi Kaneta, Tohoku Univ.
Slide 5
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) Masashi Kaneta, Tohoku Univ. 5 The
Experiments at LNS, Tohoku
Slide 6
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) The Experiments The series of
experiments by neutral kaon spectrometer at LNS, Tohoku Univ. The 1
st generation (NKS) Used TAGX spectrometer of INS and successfully
done in 2004 The first measurement of the cross-section of neutral
channel near the threshold Carbon target results: PLB651(2007)269
Liquid D 2 target results: PRC78(2008)014001 It is found that some
improvements are necessary: the forward region, and the vertical
position information in the chambers The 2 nd generation (NKS2)
Constructed in 2004-2006 from scratch Commissioning run in 2006 The
data taking with liquid D 2 target in 2006-2007 An upgrade is on
going 6 Masashi Kaneta, Tohoku Univ.
Slide 7
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) The NKS (1998-) and NKS2 (2004-)
collaboration Akita University, Akita, Japan A. Sasaki Ichinoseki
National college of Technology, Ichinoseki, Japan O. Konno
Department of Physics, Tohoku University, Sendai, Japan N. Chiga,
B. Beckford, M. Ejima, T. Fujii, Y. Fujii, T.Fujibayashi, T.
Gogami, K. Futatsukawa, O. Hashimoto, K. Hosomi, K. Hirose (a), A.
Iguchi, S. Kameoka, H. Kanda, M. Kaneta, H. Kato, D. Kawama, T.
Kawasaki, C. Kimura, S. Kiyokawa, T. Koike, T. Kon, Y. Ma, K.
Maeda, N. Maruyama, A. Matsumura, Y. Miyagi, Y. Miura, K. Miwa,
S.N. Nakamura, H. Nomura, A. Okuyama, A. Ohtani, T. Otani, M. Sato,
A. Shichijo, K. Shirotori, T. Takahashi (b), H. Tamura, N. Taniya,
H. Tsubota, K. Tsukada (c) N. Terada, M. Ukai (d), D. Uchida, T.
Watanabe, T. Yamamoto, T. Yamamoto, H. Yamauchi, K. Yokota
Laboratory of Nuclear Science, Tohoku University, Sendai, Japan T.
Ishikawa, T. Kinoshita, H. Miyahara, T. Nakabayashi, H. Shimizu, K.
Suzuki, T. Tamae, T. Terasawa, H. Yamazaki Department of Nuclear
Science, Lanzhou University, Lanzhou, China Y.C. Han, T.S. Wang
Nuclear Institute, Czech Republic P. Bydzovsky, M. Sotona Masashi
Kaneta, Tohoku Univ. 7 Student name is shown with underline (a) Now
at LNS, Tohoku University, Japan (b) Now at KEK, Japan (c) Now at
RIKEN, Japan (d) Now at Gifu University, Japan
Slide 8
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) Tagged Photon Beam Line at LNS 150
MeV electron beam from LINAC 1.2 GeV Stretcher-Booster Ring Photon
tagging system Sweep magnet Neutral Kaon Spectrometer Neutral Kaon
Spectrometer 2 8 Masashi Kaneta, Tohoku Univ.
Slide 9
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) Tagged Photon Beam at LNS Radiator
Photon beam Electron beam on carbon wire (11 m ) Tagged by electron
which has energy loss E =0.8-1.1 GeV from 1.2 GeV electron beam 6
MeV coverage per tagging counter Time resolution: ~240 ps Tagger
Backup Tagger Finger Scattered e - e - on orbit 9 Masashi Kaneta,
Tohoku Univ.
Slide 10
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18)NKS There are two arms in one dipole
magnet IH:Inner Hodoscope SDC:Straw Drift Chamber CDD:Cylindrical
Drift Chamber OH:Outer Hodoscope EV:Electron Veto No acceptance in
forward region 10 Masashi Kaneta, Tohoku Univ.
Slide 11
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18)NKS2 Masashi Kaneta, Tohoku Univ. 11
Dipole Magnet B=0.42 [T] at the center Inner Hodoscope Trigger
Start timing of TOF Outer Hodoscope Trigger Stop timing of TOF
Straw Drift Chamber Tracking (2D) Cylindrical Drift Chamber
Tracking (3D) Electron Veto Counter beam 1.0 m A vertical cross
section along beam
Slide 12
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) NKS2 Photo Masashi Kaneta, Tohoku
Univ. 12
Slide 13
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) 0.0 0.5 1.0 1.0 0.5 1.0 0.5 0.0 0.5
1.0 1.0 0.5 1.0 0.5 Masashi Kaneta, Tohoku Univ. 13 Red contour: D
2 target K 0 S production cross-section (Kaon-MAID model) Gray
contour: Acceptance of K 0 S ( ) in NKS and NKS2 K 0 S momentum
[GeV/c] Red contours: K 0 S cross-section Kaon-MAID model
calculation on a D 2 target Energy threshold 0.915 GeV in +n K 0 +
E =0.8-1.1 GeV at LNS 0.0 0.5 1.0 1.0 0.5 1.0 0.5 cos lab E =
0.9-1.0 GeV E =1.0-1.1 GeV NKS NKS2 543210543210 efficiency [%]
Comparison of Acceptances
Slide 14
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) NKS Masashi Kaneta, Tohoku Univ. 14
Results from the 1 st generation experiment NKS
Slide 15
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) Particle Identification Good
pion/proton separation TOF: ~510ps Masashi Kaneta, Tohoku Univ.
15
Slide 16
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) Decay Volume Cut Main background of K
0 S e + e from photon conversion can be rejected by opening angle
cut and Electron Veto counter from and can be rejected by decay
volume cut With the decay volume cut, the S/N increased 16 Masashi
Kaneta, Tohoku Univ.
Slide 17
International Symposium on Strangeness in Nuclear and Hadronic
Systems -SENDAI08- (Dec15-18) Invariant Mass of + - B.G.1 B.G.2
B.G.0 B.G.0: e + e (miss-ID as pions) B.G.1: from K 0 S and from
B.G.2: from and After applying decay volume cut and opening angle
cut (-0.9