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Preface
This issue of Research Report of Laboratory of Nuclear Science reports research activities of the
LNS performed in the 2006 academic/fiscal year (April 2006 – March 2007). Major research activities
are based on the electron accelerator complex consisting of the 300-MeV LINAC and the 1.2-GeV STB
ring. The accelerators have altogether provided a beam time of about 2,380 hours for various
experiments through the year.
In the GeV-ġ experimental hall, construction of a 4Į spectrometer called FOREST, which is anelectro-magnetic calorimeter for neutral meson detection, has started. At this occasion, a beam line forcounter test experiments was developed to provide low-intensity electron/positron beams with amomentum range from 200 to 800 MeV. In the experimental hall 2, commissioning of the New NKS
spectrometer has essentially finished and the D(ġ ,K0) experiments for neutral Λ particle production
has started in June. Various radioactive isotopes were produced by using high intensity beams below 50
MeV at the experimental hall 1. They were served for element analyses as well as for detailed study of
decay properties of nuclei: the highlight is the change of positron capture rate in carbon fullerene.
We hope that this Report will serve as a quick overview of the present LNS activities over a varietyof nuclear research fields.

Jirohta KASAGI
Director

Research Report of Laboratory of Nuclear Science
Volume 40, 2007
ContentsԅȅNuclear PhysicsȁԅȽˍȁStudy of Neutral Kaon Photo-Production at LNS-Tohoku

Ĳ

Petr. Bydžovský, Nobuyuki Chiga, Yu Fujii, Kenta Futatsukawa, YungChen Han,
Osamu Hashimoto, Kentaro Hirose, Kenji Hosomi, Aran Iguchi,
Takatsugu Ishikawa, Hiroki Kanda, Masashi Kaneta, Masahiro Kawai,
Taito Kawasaki, Daisuke Kawama, Shogo Kiyokawa, Takeshi Koike, Osamu Konno,
Yue Ma, Kazushige Maeda, Nayuta Maruyama, Akihiko Matsumura,
Masahiro Mimori, Kouji Miwa, Youhei Miyagi, Satoshi N. Nakamura,
Tomokazu Ohtani, Yuichi Okayasu, Atsushi Sasaki, Hajime Shimizu,
Koutarou Shirotori, Miraslav Sotona, Koutaku Suzuki, Tadaaki Tamae,
Hirikazu Tamura, Nobuhiro Terada, Kyo Tsukada, TieShen Wang,
Taku Yamamoto, Hirohito Yamazaki, and Kousuke YokotaȁԅȽˎȁElectron/Positron Test BeamlineķIshikawa Takatsugu, Ryo Hashimoto, Takashi Ishida, Jirohta Kasagi,
Shuzo Kuwasaki, Kazushige Maeda, Keichi Mochizuki, Kenichi Nawa,
Yasuyuki Okada, Yoshihito Onodera, Hajime Shimizu, Koutaku Suzuki,
and Hirohito YamazakiȁԅȽˏȁEnergy Calibration of STB-Tagger II by Using e+eȽ Pair Production

Ĳı

Koutaku Suzuki, Ryo Hashimoto, Takashi Ishida, Ishikawa Takatsugu,
Jirohta Kasagi, Shuzo Kuwasaki, Keichi Mochizuki, Kenichi Nawa,
Yasuyuki Okada, Yoshihito Onodera, Hajime Shimizu, and Hirohito YamazakiȁԅȽːȁPerformance of a Test Calorimeter of Lead Scintillating Fiber Modules

ĲĶ

Keichi Mochizuki, Ishikawa Takatsugu, Ryo Hashimoto, Takashi Ishida,
Shuzo Kuwasaki, Kenichi Nawa, Yasuyuki Okada, Yoshihito Onodera,
Hajime Shimizu, Koutaku Suzuki, and Hirohito YamazakiȁԅȽˑȁLEPS Backward Gamma Detector Reassembled

ĲĺIshikawa Takatsugu, Keichi Mochizuki, Koutaku Suzuki, Yasuyuki Okada,Ryo Hashimoto, Jirohta Kasagi, Shuzo Kuwasaki, Kenichi Nawa,
Yoshihito Onodera, Mamoru Sato, Hajime Shimizu, and Hirohito YamazakiȁԅȽ˒ȁCurrent Status of the Electro-Magnetic Calorimeter SCISSORS III
Ishikawa Takatsugu, Ryo Hashimoto, Jirohta Kasagi, Shuzo Kuwasaki,
Keichi Mochizuki, Kenichi Nawa, Yasuyuki Okada, Yoshihito Onodera,
Mamoru Sato, Hajime Shimizu, Koutaku Suzuki, and Hirohito YamazakiĳĴȁԅȽ˓ȁDevelopment of a Multi-Purpose Logic Module with the FPGAĳĸ

Kenichi Manbu, Ishikawa Takatsugu, and Hirohito YamazakiȁԅȽ˔ȁRadiation Hardness Test of GaN Diode for Irradiation with High Energy Electron Beamȁȁȁȁȁȁȁ

ĴĲ

Shinya Narita, Yusuke Yamaguchi, Yuki Chiba, Jirohta Kasagi, Fujio Hinode,and Hideyuki YukiȁԅȽ˕ȁDevelopment of Waveform Readout System for Germanium Detectors at J-PARCĴķ

Kenji Hosomi, Mifuyu Ukai, Tomokazu Otani, Takeshi Koike, Yue Ma,
Masahiro Mimori, Koji Miwa, Kotaro Shirotori, and Hirokazu TamuraԆȅRadiochemistryȁԆȽˍȁNoble Gas and Bulk Chemistry Study of Three Eucrites
Juvinas, Stannern and Dhofar 007

Ĵĺ

Mitsuyo Takeda, Yasuji Oura, and Mitsuru EbiharaԇȅList of Publicationȁȁȁȁȁȁȁ

ĵĶԈȅApproved ExperimentsȁԈȽˍȁFormer Term in 2006ĵĺȁԈȽˎȁLatter Term in 2006Ķı‫ړ‬ၑࡄࡄ‫ݪ‬༭࣬ȁలĵı‫ے‬ȁ࿒ȁষԅȅࡔঊ‫ړ‬໤ၑȁԅȽˍȁStudy of Neutral Kaon Photo-Production at LNS-Tohoku

Ĳ

Petr. BydžovskýȄ୷ٖ૞ࢨȄ൥֔ȁ࿹ȄඵΜ୼࠲ఊȄ‫܀‬ȁഥ଼Ȅ‫ུޘ‬ȁহȄᎢଳ࠲ఊ჊Ȅळࡉ࠲ඵȄ࢛֔Տ၊Ȅ୞୼ܲ঄Ȅ૰നࢼਏȄ߄നٗংȄ‫ୃࣣع‬ୀȄ୼ॄణറȄ୼‫ۼ‬ఱٚȄୄ୼જࢁȄ઀౻໌঎Ȅࣽ࿤ȁᓚȄ෯ȁȁ‫ק‬Ȅஜനგ࿆Ȅ‫܃‬५ඣဇఊȄઐఆઆ຃Ȅ२૩ٗࢬȄ२ႊࢼংȄ‫ݠ‬ઽါ໹ȄಎఆȁഓȄఱ౓࿻გȄ‫ؖ‬հဎ֚Ȅऎș࿐࢚ȄୄକȁรȄฒುࢳఊ჊ȄMiraslav SotonaȄႝ࿐ࣈఽȄޮࢺ಑ྶȄനఆဉგȄ঳നܽࢬȄ೓നȁީȄTieShen WangȄ५ུȁఽȄ५ॄۘ૾Ȅ‫؍‬നࢣٚȁԅȽˎȁElectron/Positron Test Beamlineķ୞୼ܲ঄Ȅ‫ུޘ‬ȁၮȄ୞നࢣংȄ‫ڦ‬࿐হ჊ఊȄ߭ॄਜ२Ȅஜനგ࿆Ȅབ࠮ࠃ֚Ȅථȁ࠲֚Ȅ‫ؖ‬നࢫ࿻‫ܮ‬Ȅ઀࿤঳݅૽ȄୄକȁรȄ५ॄۘ૾ȁԅȽˏȁEnergy Calibration of STB-Tagger II by Using e+eȽ Pair Production

Ĳı

ႝ࿐ࣈఽȄ‫ུޘ‬ȁၮȄ୞നࢣংȄ୞୼ܲ঄Ȅ‫ڦ‬࿐হ჊ఊȄ߭ॄਜ२Ȅབ࠮ࠃ֚Ȅථȁ࠲֚Ȅ‫ؖ‬നࢫ࿻‫ܮ‬Ȅ઀࿤঳݅૽ȄୄକȁรȄႝ࿐ࣈఽȄ५ॄۘ૾ȁԅȽːȁPerformance of a Test Calorimeter of Lead Scintillating Fiber ModulesĲĶབ࠮ࠃ֚Ȅ୞୼ܲ঄Ȅ‫ུޘ‬ȁၮȄ୞നࢣংȄ߭ॄਜ२Ȅථȁ࠲֚Ȅ‫ؖ‬നࢫ࿻‫ܮ‬Ȅ઀࿤঳݅૽ȄୄକȁรȄႝ࿐ࣈఽȄ५ॄۘ૾ȁԅȽˑȁLEPS Backward Gamma Detector ReassembledĲĺ୞୼ܲ঄Ȅབ࠮ࠃ֚Ȅႝ࿐ࣈఽȄ‫ؖ‬നࢫ࿻‫ܮ‬Ȅ‫ུޘ‬ȁၮȄ‫ڦ‬࿐হ჊ఊȄ߭ॄਜ२Ȅථȁ࠲֚Ȅ઀࿤঳݅૽Ȅऎ൥ȁ‫מ‬ȄୄକȁรȄ५ॄۘ૾ȁԅȽ˒ȁCurrent Status of the Electro-Magnetic Calorimeter SCISSORS IIIĳĴ୞୼ܲ঄Ȅ‫ུޘ‬ȁၮȄ‫ڦ‬࿐হ჊ఊȄ߭ॄਜ२Ȅབ࠮ࠃ֚Ȅථȁ࠲֚Ȅ‫ؖ‬നࢫ࿻‫ܮ‬Ȅ઀࿤঳݅૽Ȅऎ൥ȁ‫מ‬ȄୄକȁรȄႝ࿐ࣈఽȄ५ॄۘ૾ȁԅȽ˓ȁDevelopment of a Multi-Purpose Logic Module with the FPGAĳĸධ໐࠲֚ȄୄକȁรȄ୞୼ܲ঄ȁԅȽ˔ȁRadiation Hardness Test of GaN Diode for Irradiation with High Energy
Electron BeamĴĲ଼ന૨࿟Ȅ५࢛ဉٚȄ୷ဩဈܽȄ‫ڦ‬࿐হ჊ఊȄ඾੄ີআဎȄࠫઽਜ࣐ȁԅȽ˕ȁJ-PARC ৘ࡑဥΊσζΣ;θ࠿੄‫͈ܕ‬෨ࠁඋ͙੄༹̱͈‫ٳ‬อळࡉ࠲ඵȄֹူ๼ൃȄఱ౓࿻გȄ઀౻໌঎Ȅ෯ȁȁ‫ק‬Ȅ२૩ٗࢬȄ२ႊࢼংȄฒುࢳఊ჊ȄനఆဉგĴķԆȅ༶ৣ‫ڠا‬ȁԆȽˍȁˏਅξȜ·ρͼΠ᳖୞ȪDhofar 007, Juvinas, Stannernȫ͈‫΄ܛ‬Α̤͍͢ȁȁȁȁȁ஠‫ڠا܊‬ழ଼ͅ‫ݪࡄ̳ͥ۾‬Ĵĺಅന࢕ଲȄఱ‫׆‬ణ঄Ȅ٬Ⴧࡔਰԇȅა໲ςΑΠȁȁȁȁȁȁȁ

ĵĶԈȅ‫ه‬ఴन఼ࠫ‫ض‬ȁԈȽˍȁ໹଼ĲĹාഽஜ‫ܢ‬ĵĺȁԈȽˎȁ໹଼ĲĹාഽࢃ‫ܢ‬Ķıԅȅ/VDMFBS1IZTJDTResearch Report of Laboratory of Nuclear Seience, Tohoku University Vol. 41 (2008)

1(LNS Experiment : #2552, #2565)

Study of Neutral Kaon Photo-Production at LNS-Tohoku
P. Bydžovský1 , N. Chiga 2 , Y. Fujii 2 , K. Futatsukawa2 , Y.C. Han 6 ,O. Hashimoto 2 , K. Hirose 4 , K. Hosomi 2 , A. Iguchi 2 , T. Ishikawa 4 ,H. Kanda 2 , M. Kaneta 2 , M. Kawai 2 , T. Kawasaki 2 , D. Kawama 2 ,S. Kiyokawa 2 , T. Koike 2 , O. Konno 5 , Y. Ma 2 , K. Maeda 2 , N. Maruyama 2 ,A. Matsumura 2 , M. Mimori 2 , K. Miwa 2 , Y. Miyagi 2 , S.N. Nakamura 2 ,T. Ohtani 2 , Y. Okayasu 2 , A. Sasaki 3 , H. Shimizu 4 , K. Shirotori 2 ,M. Sotona 1 , K. Suzuki 4 , T. Tamae 4 , H. Tamura 2 , N. Terada 2 , K. Tsukada 2 ,T.S. Wang 6 , T. Yamamoto 2 , H. Yamazaki 4 , and K. Yokota 2
1
2
3

Department of Physics, Tohoku University, Sendai 980-8578

Department of Electrical and Electronic Engineering, Akita University, Akita 010-8502
45

Nuclear Physics Institute, 25068, Řež, Czech Republic

Laboratory of Nuclear Science, Tohoku University, Sendai 982-0826

Department of Electrical Engineering, Ichinoseki National College of Technology, Ichinoseki
021-8511
6

School of Nuclear Science and Technology, Lanzhou University,
Tianshuinan Road 222, Lanzhou 730000, China§ 1. Introduction
The investigation of the kaon production on a nucleon by the electromagnetic interaction provides
invaluable information on the strangeness production mechanism, strength of meson-baryon coupling
constants and structure of hadrons, being labeled by the strangeness degree of freedom. Such studies using beams of real photons and electrons have been conducted experimentally and theoretically since the1950’s, taking advantage of the electromagnetic interaction that is understood better than the hadronicinteraction. Until now, the experimental studies have been carried out in p(γ, K + )Λ , p(γ, K + )Σ0 andp(γ, K 0 )Σ+ reactions among six isospin channels ( [1], [2]). However, there are no data for the otherthree channels on a neutron. Theoretically, phenomenological models have been constructed based on
measured channels so far. The isobar models, Kaon-MAID [3] and SLA [4], were adopted in the present
analysis. The predictions of the photon energy dependence and the kaon angular distribution of theother three channels on a neutron using these models are quite different.
The lack of the key data for strangeness photoproduction of the three channels on a neutron is dueto the experimental difﬁculties to measure neutral kaons and to prepare a neutron target. The measurement of these three strangeness production channels provides much information on the strangenessphotoproduction mechanism. In particular, the n(γ, K 0 )Λ reaction has following features. (1) Since nocharge is involved, the t-channel Born term does not contribute. (2) It is a mirror reaction to p(γ, K + )Λ. For the hyperon resonance exchange terms, a coupling constant, gKΣN , changes its sign from the2isospin symmetry, gK 0 Σ0 n = −gK + Σ0 p , resulting the different interference effect. Furthermore, the number of resonances to be considered is small in the threshold region. Therefore, the n(γ, K 0 )Λ reaction is
expected to play an essential role to investigate the strangeness photoproduction mechanism.
We have already taken exploratory data quite successfully with use of Neutral Kaon Spectrometer(NKS) at LNS-Tohoku in 2003 and 2004. We intend to extend the previous experiment by considerably upgrading the original neutral kaon spectrometer to a completely new neutral kaon spectrometer(NKS2), fully replacing the spectrometer magnet, tracking detectors and all the trigger counters. The
new spectrometer NKS2 has signiﬁcantly larger acceptance for neutral kaons compared with NKS, particularly covering forward angles and much better invariant mass resolution. The estimated acceptanceof NKS2 is about 3 to 4 times (depend on momentum and model) larger for KS0 than that of NKS. Additionally, it is about 8 to 10 times larger for Lambda. With this advantage, we expect simultaneous
measurements of KS0 and Λ. Additionally, we plan to measure other strangeness production channels
and also Λ hyperon polarization in γ + n and γ + p reactions.
In this report, we present a status of NKS2 experiment. The NKS results are found in elsewhere [5,6].

§ 2. The NKS2 Experiment
The NKS2 spectrometer is located the BM4 beam line of the second experimental hall of Laboratoryof Nuclear Science (LNS), Tohoku University (see Fig. 1). The incident beam from LINAC has 0.2 GeVof the beam energy and is accelerated up to 1.2 GeV in Stretcher-Booster (STB) Ring. The photon beam
is created as bremsstrahlung of electron by a carbon wire at STB Tagger system of Bending Magnet 4(BM4). There is a dipole magnet which is called the sweep magnet for e+ e− from photon conversion.
The sweep magnet is the same one which is used in the previous experiment NKS.
The spectrometer is placed following the sweep magnet. The main magnet is a dipole which is renovated from a cyclotron magnet of Cyclotron RI center of Tohoku University (it is so called 680 magnet).
Detectors of NKS2 are: Inner Hodoscope (IH), Straw Drift Chamber (SDC), Cylindrical Drift Chamber(CDC), Outer Hodoscope (OH), and Electron Veto counter (EV). Figure 2 shows detector position and 3D
views are shown in Figs. 3 and 4. The detail description of the beam line and the spectrometer will beshown in the following sections.

§ 3. Results of the NKS2 experiment
The data taking for commissioning runs was carried out in Jan. Mar, Jun., and Sep. 2006 using thecarbon target. During those runs, we had studied detector performance, data acquisition system, andtrigger rate. The data taking using NKS2 was done in Nov. and Dec. 2006, and Jan. and Jun. 2007.
A preliminary invariant mass distribution of π + π − pairs in 0.8 < Eγ < 1.1 GeV is shown in Fig. 5.
The number of tagged photons for the distribution was 3.2 × 1011 from 2006’s runs.
The events that have two tracks and more was selected. The particle identiﬁcation was done on 2
dimensional cut on TOF and momentum. After positive and negative pions was identiﬁed in the same3

Fig.1.

The outline of the second experimental hall of LNS (see text in detail).

OHV

OHH

CDC

SDC
IH
20 cm

Targetg Beam1m
g Beam

Fig.2.

A schematic view of NKS2. The photon beam direction is bottom to top in the ﬁgure. The
target holder is at center of magnet. The detectors are (the order is center to outer): Inner
Hodoscope (IH), Straw Drift Chamber (SDC), Cylindrical Drift Chamber (CDC), Outer
Hodoscope (OH, Vertical (OHV) and Horizontal (OHH) ), and Electron Veto counter (EV).
Note that EV is placed at downstream of OHV but not shown the ﬁgure.

4

Fig.3.

A 3D view of the spectrometer viewed from upstream of beam line. We can see a part of
OHH on the magnet yoke and OHV around magnet coil.

Fig.4.

A 3D view of the spectrometer viewed from downstream of beam line. There are OHVaround the magnet coil and OHH on the magnet yoke. The EV counters are placed following OHV. The OHV and EV counters are supported by aluminum chassis.

Number of counts

5

P

ar
n
i
relim

y

2

Invariant mass [ GeV / c ]Fig.5.

The invariant mass distribution of π + π − pairs in 0.8 < Eγ < 1.1 GeV.

event, the decay vertex was reconstructed from the two tracks. We required −0.9 < cos θOA < 0.8(where θOA is an opening angle of two tracks) to select KS0 candidate. We required an opening angle cutof two tracks to remove e+ e− background. A decay volume cut was necessary to remove a background ofresonances (e.g., ρ, ω). Since photoproduced vector mesons and nucleon resonances decay in the target
region and create π + π − background, we did not employ events which have their decay vertex positionin the target cell. We employ events which have the decay vertex position at outside of the target cell toremove large contribution of hadronic background.
We have an upgrade plane of the spectrometer, that we will extend the acceptance by changing SDCwith a 3D tracking chamber. With this advantage, we expect simultaneous measurements of KS0 and Λ.
Additionally, we plan to measure other strangeness production channels and also Λ hyperon polarizationin γ + n and γ + p reactions.

Acknowledgement
This work is supported by Grant-In-Aid for Scientiﬁc Research from The Ministry of Education ofJapan, Nos. 09304028, 12002001, 14740150 and 16GS0201.

References[1]

D.S. Caran et al.: Phys. Rev. Lett. 90 (2003) 131804.

[2]

R.G.T. Zegers et al.: Phys. Rev. Lett. 91 (2003) 092001.

[3]

F.X. Lee, T. Mart, C. Bennhold, and L.E. Wright: Nucl. Phys. A695 (2001) 237.

[4]

T. Mizutani, C. Fayard, G.H. Lamot, and B. Saghai: Phys. Rev. C58 (1998) 75.

[5]T. Watanabe et al.: Phys. Lett. B651 (2007) 269.

[6]

K. Tsuakda et al.: arXiv:0712.0657(nucl-ex).

6

Research Report of Laboratory of Nuclear Seience, Tohoku University Vol. 40 (2007)(LNS Experiment : #2563)

Electron/Positron Test Beamline
T. Ishikawa1 , R. Hashimoto1 , T. Ishida1 , J. Kasagi1 , S. Kuwasaki1 , K. Maeda2 ,K. Mochizuki1 , K. Nawa1 , Y. Okada1 , Y. Onodera1 , H. Shimizu1 , K. Suzuki1 ,and H. Yamazaki1
1

Laboratory of Nuclear Science, Tohoku University, Sendai, 982-0826

2

Department of Physics, Tohoku University, Sendai, Miyagi 980-8578

An electron/positron beamline for testing detectors has been constructed by utilizing a charge
sweeping magnet RTAGX, which can analyze the momentum of electrons and positrons at a ﬁxed bending angle. The measured energy, proﬁle, and intensity of the beam are reported together with a simulation result.

§ 1. Electron/Positron Beamline for Testing Detectors
A dipole electromagnet RTAGX was installed two years ago [1] in the GeV-γ experimental hall,where meson production experiments have been conducted with an incident γ beam [2]. Besides sweeping out undesirable charged particles in the γ beam, the RTAGX can provide momentum-analyzed electrons or positrons at a ﬁxed bending angle. We have desired a beamline where performance tests canbe made for many kinds of detectors. Thus an electron/positron beamline has been constructed in the
GeV-γ experimental hall for testing detectors. The beamline consists of a converter, the RTAGX magnet,
and lead apertures as depicted in Fig.1. A Au foil, one of the converters, with a thickness of 20 μm is

φ1073
100
φ105

30.00

q

Au foil Pb Aperture

24

45

100
878

RTAGX

Pb Aperture
Positron/Electron Beam

Fig.1. Schematic view of the electron/positron beamline for detector test. The beamline comprises a converter, a dipole electromagnet RTAGX, and entrance and exit lead apertures.
Electrons/positrons passing through the lead apertures are used as a beam.

7
placed 878 mm upstream of the pole center of the RTAGX. There is a 100 mm thick lead aperture justbehind the converter. Another 100 mm thick lead aperture with a diameter of 20 mm is placed 2445 mm
downstream at −30◦ with respect to the axis of the incident γ beam. A vacuum chamber and a vacuum
pipe were installed between two lead apertures on 23rd Apr. in 2007.
The incident γ beam coming into the GeV-γ experimental hall irradiates the converter in front of the
RTAGX. Some photons in the beam are converted into electron-positron pairs. The generated electronsand positrons are bent by the RTAGX according to their momenta. Then semi-monochromatic electronsor positrons passing through the lead apertures are used as a beam.

§ 2. Estimated Energy and Resolution
The energy and resolution of the beam for a given RTAGX current are estimated by a simulation
code based on GEANT3 with a corresponding magnetic ﬁeld map [1, 3]. Figure 2 shows the estimated

900
800
700
600
500
400
300
200
100
0

3
Energy Resolution σE/E (%)

Energy E (MeV)beam energy as a function of the RTAGX current and the energy resolution versus the beam energy.

2.5
2

1.5
1

0.5

0

100

200 300 400
Current I (A)

500

0

0

200 400 600
Energy E (MeV)

800

Fig.2. Estimated energy and resolution of the electron/positron beam with a simulation basedon GEANT3. The left panel shows the mean energy as a function of RTAGX current. The
right panel shows the energy resolution as a function of the beam energy. The circle andsquare markers show the data points when the beam
 travels in the air and in the vacuum,
respectively. Data points are ﬁtted with the form P1 E −2 + P2 E −1 + P3 + P4 E.

The electron/positron beam energy is almost proportional to the RTAGX current. The value of theenergy in MeV corresponds roughly to twice of that of the current in ampere. The energy resolution as afunction of the energy is described as
σE(125.9 ± 13.5)(7.49 ± 0.26) × 105−+ (0.977 ± 0.028) − (3.9 ± 0.2) × 10−4 E(1)
(E) =
2
E
E
E
when electrons or positrons travel in the air, while that is described as
(8.6 ± 78.1)(1.08 ± 0.15) × 105
σE−+ (0.695 ± 0.149) − (2.1 ± 1.1) × 10−4 E (2)
(E) =
E
E
E2
when they travel in the vacuum. The numerical data are given in Ref. [4].

8

§ 3. Measured Beam Energy and Intensity
The beam energy was measured with a lead glass Čerenkov counter. The beam proﬁle was also measured with a beam proﬁle monitor (BPM). The BPM consists of two layers of scintillating ﬁber (SciFi)
hodoscopes, each of which is made up with 16 SciFi modules. The ﬁber measures 3 × 3 mm2 in crosssection. The upstream and downstream layers determine x and y positions from responded ﬁbers, respectively.
Figure 3 shows the measured energy distributions, and the beam proﬁle for the RTAGX currentof 230 A. The measured energy is consistent with an estimated one, although the energy spread of thebeam is not detectable because of poor energy-resolution of the lead glass counter. The size of the beam
spot is about 50 mm in diameter at the place about 7 m from the center of the RTAGX.

a)

02
058 A
2
10 A
2
15 A
5
21 A
0
26 A
9
33 A
401 A
470 A
5
A

Figure 4 shows the beam intensity as a function of the RTAGX current.

b)

800

20

700

y (mm)Counts

15
10

600

5

500

0

400

-5

-10

300

-15

200

-20
0

200

400

600

800 1000 1200

Lead Glass ADC

100
-20

-10

0
10
x (mm)

20#Positrons / #Tagger 116 Hits (x 10 -3)

Fig.3. a) Measured beam energy distribution for several RTAGX currents. The unit of energy
is arbitrary (ADC channel). b) Measured beam proﬁle for the RTAGX current of 230 A.
Both data were measured before the vacuum chamber had been installed.

6
5
4
3
2
1
0

0

50

100 150 200 250 300 350 400 450 500
RTAGX Current (A)Fig.4. Intensity of the positron beam as a function of the RTAGX current with a converter of 20
μm thick Au foil. The intensity is normalized by the counting rate of the 116th channelof the STB-Tagger II.

9Since the beam intensity depends on the circulating electron current in the STretcher Booster ring,
it is normalized by the counting rate of the 116th channel of the STB-Tagger II [5]. More intense beam
can be obtained with a thicker converter. So far, the maximum intensity of the positron beam is about
700 kcps with an 8 mm thick Cu converter.

References[1]

T. Ishikawa et al.: Research Report of LNS, Tohoku University 39 (2006) 39.

[2]

H. Shimizu et al.: Research Report of LNS, Tohoku University 37 (2004) 13.

[3]

T. Ishikawa: Internal GeV-γ analysis notes Nos. 20 and 34 (2006).

[4]

T. Ishikawa: Internal GeV-γ analysis note No. 43 (2007).

[5]

T. Nakabayashi et al.: Research Report of LNS, Tohoku University 37 (2004) 17.

10

Research Report of Laboratory of Nuclear Seience, Tohoku University Vol. 40 (2007)(LNS Experiment : #2564)

Energy Calibration of STB-Tagger II by Using e+e− Pair
Production
K. Suzuki, R. Hashimoto, T. Ishida, T. Ishikawa, J. Kasagi, S. Kuwasaki,
K. Mochizuki, K. Nawa, Y. Okada, Y. Onodera, H. Shimizu, and H. Yamazaki
Laboratory of Nuclear Science, Tohoku University, Sendai, 982-0826
The energy calibration of a bremsstrahlung tagging system STB-Tagger II was carried out by using
a dipole magnet RTAGX. The tagged photon energy was determined by a momentum analysis of e+ e−pairs converted from bremsstrahlung photons at two energies of STB circulating electrons. The relative
relation was obtained between the tagged photon energy for 920 MeV circulating electrons and that for1200 MeV electrons. In this report, We present the method and the result of the energy calibration.

§ 1. Introduction
A tagged photon beamline has been constructed in the GeV-γ experimental hall at Laboratory of
Nuclear Science (LNS), Tohoku University [1]. We insert a radiator made of a carbon ﬁber, 11 μm in
diameter, into circulating electrons in the Stretcher-Booster (STB) ring to generate a high energy photon
beam. The electrons strike the radiator just upstream from the bending magnet BM5 of the STB ring,and produce bremsstrahlung photons which are used as a beam. Recoiled electrons are analyzed by
the BM5 and detected with a tagging system called STB Tagger II, which consists of 116 telescopes of
two-layer scintillating ﬁbers [2]. The energy Eγ of a produced photon is determined by the energy of therecoiled electron Ee and that of the circulating electron E0 as
Eγ = E0 − Eebecause the energy transferred to the nucleus is negligibly small. Thus Ee has to be measured precisely to provide a deﬁnite Eγ . However, there are some elements having slightly unknown factors in
the STB Tagger II. The map of the magnetic ﬂux in BM5 is not determined completely. The positionand direction of the recoiled electron emitting a bremsstrahlung photon are not known precisely at theradiator. And the exact position of STB Tagger II is not well known. Therefore the energy calibration isrequired for STB Tagger II. To determine Ee , Eγ has to be given conversely, which has so far been madewith two methods.
1. Missing mass MX analysis for the γ + p → π 0 + X process [3], and
2. Direct Measurement of Eγ with a lead glass Cherenkov counter [4].
In the former method, however, there is an uncertainty in the vertex point of the π 0 decay, and theenergy and position resolutions for incident photons are not good enough for this purpose. In the latter
case, the energy response of the lead glass Cherenkov counter is not precisely investigated. These two
methods did not work very well.

11
The tagged photon energy Eγ can be obtained by measuring momenta of the e+ e− pair converted
from the incident photon. Eγ is given as a sum of the e+ and e− energies Ee+ and Ee− , namely
Eγ = Ee+ + Ee− .

(1)

We have performed meson photoproduction experiments with an electro-magnetic calorimeter SCISSORS II to study nucleon resonances, using a tagged photon beam. Two circulating-electron energiesof 920 and 1200 MeV have been selected to cover the incident photon energy from 600 to 1150 MeV.
We can make a consistency check for STB Tagger II by comparing the overlap energy region measured
under these different conditions of the electron energy. In this measurement, therefore, a dipole magnet
RTAGX [5] is operated at a ﬁxed current to analyze the momentum of the e+ and e− , regardless of theelectron energy.

§ 2. Experiment
We used the RTAGX magnet for the momentum analysis of e+ e− pairs. A 20 μm thick Au foil
was placed in front of RTAGX to produce e+ e− pairs from the tagged photons. Electrons/positrons
having different momenta were bent with different curvature by RTAGX , and were detected with two
scintillating ﬁber hodoscopes located behind RTAGX. Each scintillating ﬁber measures 3×3 mm2 in crosssection, and 16 ﬁbers are arranged in a hodoscope. One hodoscope was placed 1850 mm downstream fromthe center of RTAGX and at −46.6◦ with respect to the beam axis. The other hodoscope was movable so
as to detect various energy electrons. Figure 1 shows the experimental setup for this energy calibration.

Rail +side
Movable Hodoscope

23.32㫦

Rail Position 709
31.38㫦

1018

Rail Position 1143

e−Fixed Hodoscope

902

Rail 723e+

481

46.63㫦

Yoke
1073

Pole
Coil

878

2400
400

Au 0.02 mm

Pb collimator
㱏-ray

Fig.1. Experimental setup for the energy calibration of STB-Tagger II. The e+ e− pairs are generated in the interaction of incident photons with a Au foil, and are detected by a ﬁxed
scintillating ﬁber hodoscope and a movable one.

12
A triple coincidence signal from STB-Tagger II and two scintillating ﬁber hodoscopes was used toform a trigger for the data acquisition:(trigger) = (tagger) ⊗ (ﬁxed hodoscope) ⊗ (movable hodoscope).
We measured the energy of each tagged photon deﬁned with STB Tagger II using this trigger by detecting an e+ e− pair generated from the tagged photon. The experiment was performed for two different
electron energies of 920 and 1200 MeV.

§ 3. Data Analysis
A pair of e+ and e− were detected with the ﬁxed and movable hodoscopes, respectively. Energies of
e+ and e− were determined from the position of responding ﬁbers in these hodoscopes. Here, the ﬂight
path of e+ /e− with a given energy was calculated by utilizing the ﬁeld map of RTAGX, where the energy
loss of e+ /e− was taken into account in the Au foil and the air. The magnetic ﬂux of RTAGX is described
elsewhere [6, 7]. Figure 2 shows the e+ /e− energy as a function of the bending angle determined by a
responding ﬁber.
㪊㪇

1200

㪈㪇 㪋

㪋㪇㩷㫅㫊

㫋㩿㫄㫆㫍㪀㩷㪄㩷㫋㩿㪫㪸㪾㪾㪼㫉㪀㩷㩿㫅㫊㪀Energy (MeV)

1000
800
600
400

㪉㪇
㪈㪇 㪊

㪈㪇
㪇

㪈㪇 㪉

㪄㪈㪇

200

㪈㪇

㪄㪉㪇

㪈㪉㩷㫅㫊
0
10

20

30

40

50

60

70

Bending angle (degree)+−

Fig.2. The e /e energy as a function of thebending angle.

㪄㪊㪇
㪄㪊㪇

㪄㪉㪇

㪄㪈㪇

㪈㪉㩷㫅㫊
㪇

㪈㪇

㪉㪇

㪊㪇

㪈

㫋㩿㪽㫀㫏㪀㩷㪄㩷㫋㩿㪫㪸㪾㪾㪼㫉㪀㩷㩿㫅㫊㪀Fig.3. Timing Correlation between the movable and the ﬁxed hodoscope.

Since the intensity of the bremsstrahlung photons was more than 10 MHz, there was a large fractionof accidental coincidence events. To estimate the number of true coincidence events, we made a twodimensional plot of the timing signals from the movable and ﬁxed hodoscopes. Figure 3 shows thetiming correlation between the movable and ﬁxed hodoscopes. The total area of the two-dimensional
plot is divided into 16 regions by broken lines, the center region is the prompt area, and the otherregions correspond to background events. The background events in the prompt area were subtractedwith the method of two-dimensional side band subtraction. This method is described elsewhere [8, 11].
The energy of a tagged photon can be obtained with a sum of the e+ and e− energies as expressedin Eq. (1). Figure 4 shows e+ e− energy sum distributions corresponding to tagger channel, 1, 70 and

13
-5

Yield

x 10

-4

Tag 1

x 10

-4

Tag 70

x 10

0.6

0.15

0.3

0.4

0.1

0.2

0.2

0.05

0.1

0

0

0
800

1000

1200

Tag 116

800

1000

1200

800

1000

1200

Ee- + Ee+ (MeV)
Fig.4. Energy sum distributions of e+ and e− converted from the tagged photons corresponding
to tagger channel, 1, 70 and 116. Each curve is a Gaussian function ﬁtted to the data.

116 after the background subtraction of accidental coincidence events. The centroid of the e+ e− energy
sum is determined by ﬁtting a Gaussian function to the data.

§ 4. Tagged Photon Energy
The energy of photons tagged with STB Tagger II was calibrated by measuring the energies ofe+ e− pairs. STB-Tagger II covers the tagged photon energy range from 579 to 890 MeV for 920 MeV
circulating electrons, and 752 to 1155 MeV for 1200 MeV electrons. Since the RTAGX coils carried aﬁxed current, the tagged photon energy for 920 MeV electrons was determined relatively to that for1200 MeV electrons. In Fig. 5, the measured photon energies are plotted as a function of the telescope
number in STB Tagger II.

1200
1100

1200 MeV mode
Energy (MeV)

1000
900
800

920 MeV mode

700
600
5000

20

40

60

80

100

120

Telescope number
Fig.5. Relation between the photon energy and the telescope number in STB Tagger II at two
circulating-electron energies of 920 and 1200 MeV.

14
We made another calibration by measuring the threshold energy of the γ + p → η + p reaction.
This calibration identiﬁed the tagging telescope corresponding to the incident photon having the η production threshold energy. The threshold photon energy in the γ + p → η + p reaction can be calculated
precisely, that is Eγ = 707.25 MeV. We compared the η threshold energy with the tagged photon energy
corresponding to the η threshold point by the momentum analysis for e+ e− pairs. It turned out thatthe tagged photon energy determined by the momentum analysis was 0.63% larger than the thresholdenergy [9]. This difference was mainly caused by an overall normalization uncertainty in the magnetic
ﬁeld of RTAGX. Thus the normalization uncertainty was resolved [10]. The geometrical errors arise
from a position measurement uncertainty of the ﬁxed and movable hodoscopes, a setup uncertainty ofthe movable hodoscope location, and a position uncertainty of the incident photon beam [11]. The total
uncertainty of the tagged photon energy is 0.3%.

References[1]

H. Shimizu et al.: Research Report of Laboratory of Nuclear Science, 37 (2004) 13.

[2]

T. Nakabayashi et al.: Research Report of Laboratory of Nuclear Science, 37 (2004) 17.

[3]

S. Suzuki: Master’s thesis, Department of Physics, Tohoku University (2005).

[4]

T. Ishikawa: Internal GeV-γ analysis note No.15 (2006).

[5]

T. Ishikawa et al.: Research Report of Laboratory of Nuclear Science, 39 (2004) 39.

[6]

T. Ishikawa: Internal GeV-γ analysis note No.20 (2006).

[7]

T. Ishikawa: Internal GeV-γ analysis note No.34 (2006).

[8]

T. Nakabayashi: Internal GeV-γ analysis note No.18 (2006).

[9]

T. Ishikawa: Internal GeV-γ analysis note No.57 (2007).

[10] K. Suzuki: Internal GeV-γ analysis note No.59 (2007).
[11] K. Suzuki: Internal GeV-γ analysis note No.35 (2007).

Research Report of Laboratory of Nuclear Seience, Tohoku University Vol. 40 (2007)

15(LNS Experiment : #2536, #2582)

Performance of a Test Calorimeter of Lead Scintillating
Fiber Modules
K. Mochizuki, T. Ishikawa, R. Hashimoto, T. Ishida, S. Kuwasaki, K. Nawa,
Y. Okada, Y. Onodera, H. Shimizu, K. Suzuki, and H. Yamazaki
Laboratory of Nuclear Science, Tohoku University, Sendai, 982-0826

A new electro-magnetic (EM) calorimeter complex FOREST comprises three independent calorimeters, covering a solid angle of about 4π sr in total. The Backward Gamma detector brought from SPring8/LEPS is employed to cover the central part of FOREST. Backward Gamma consists of lead scintillatingﬁber (Lead/SciFi) detector modules. The performance of a test calorimeter made up with 9 Lead/SciFi
detector modules of Backward Gamma has been studied by using a positron beam with energies up to
800 MeV.

§ 1. Experimental Setup
The performance study of a test calorimeter was made at the electron/positron beamline dedicatedto testing detectors at LNS. The test calorimeter is made up with Lead/SciFi detector modules stacked
in a 3 × 3 array, which is a small portion corresponding to a polar angle from 60◦ to 90◦ of the Backward Gamma detector. Momentum-analyzed positrons were used as an incident beam with the energy
ranging from 200 to 800 MeV . A beam proﬁle monitor (BPM) was used to specify the position of theincident positrons. BPM consists of two layers of scintillating ﬁber (SciFi) hodoscopes. Each hodoscopeis composed of 16 SciFi modules with a cross section of 3 × 3 mm2 . The upstream and downstream layers
determine the x and y positions of the incident positron, respectively. Figure 1 shows the experimental
setup for the performance study of the calorimeter.
The trigger condition for the data acquisition system is described as[x ﬁber OR] ⊗ [y ﬁber OR],(1)

where ⊗ means coincidence of signals. The maximum trigger rate was 2 kHz and a fraction of accidental
coincidence events was negligibly small. The energy calibration for the Lead/SciFi detector modules wasmade by using 300, 460, 590, and 800 MeV positrons injected on to the central region (6×6 mm2 ) of each
module one by one. The detector module has the shape of a truncated pyramid. Therefore the position
and the tilted angle of the calorimeter were set so that the beam axis was perpendicular to the front faceof the module of interest. Then the gain of each detector module was adjusted.

16

33 Lead/SciFi modules
33 Lead/SciFi modules
1616 fibers

1616 fibers
Beamline

Fig.1. Experimental setup for the performance study of a test calorimeter comprised of 9
Lead/SciFi detector modules. The 16 × 16 scintillating ﬁber hodoscopes are placed in
front of the calorimeter to determine the position of incident positions.

§ 2. Energy Response
The deposited energy in the calorimeter is obtained by summing up the measured energies with 9
detector modules as
E=

9


Ej .

(2)

j=1

The positrons injected on to the central region (6×6 mm2 ) were selected in the energy measurement tosuppress the energy leakage out of the detector modules in the lateral direction. The linearity of theenergy response was checked with the ratio of the reconstructed energy to the incident positron energy.
Figure 2a) shows the ratio as a function of the incident energy. The normalization of the reconstructedenergy is arbitrary. A linear function rμ (Ei ) of the incident energy Ei was ﬁtted to the measured ratiorμ . The ﬁtted result is expressed asrμ (Ei ) = (1.1307 ± 0.0022) − (5.0769 ± 0.3433) × 10−5 Ei ,(3)

where Ei is in MeV. The non-linearity of the energy response was found to be less than 6% for theincident beam energies from 200 to 800 MeV.
The energy resolution σE /E can be evaluated with a Gaussian mean μ and a width σ of the reconstructed energy distribution as 2 1/2

2
σE
σb
σ
−
,
=
E
μb
μ

(4)

where the effect of beam energy spread σb /μb [3] is subtracted. Figure 2 b) shows the measured energy
resolution as a function of the incident energy. The energy resolution σE /E may be expressed as
1/2

2

a1
σE
a2 2
2
+ √
+ a0
.
(5)
=
E
E
E
The function (5) is ﬁtted to the data to give the result,
1/2

2 
2
σE
1.93 ± 0.11
6.91 ± 0.08
2√+
+ (0.00 ± 0.92),(Ei ) =
Ei
E
Ei

(6)

1.20
1.18

a)
Energy Resolution (%)

ADC Peak Position/Incident Energy

17

1.16
1.14
1.12
1.10
1.08
1.06
0

200 400 600
800Incident Energy E (MeV)

20
18 b)
16
14
12
10
8
6
4
2
00
0.2
0.4
0.6
0.8
Incident Energy E (GeV)

Fig.2. The energy response as a function of the incident positron energy. a) The ratio of
the reconstructed energy to the incident energy. The normalization factor is arbitrary.
The data are ﬁtted with a linear parametrization 1.1307 − 5.0769 × 10−5 Ei . b) The
measured energy resolution. The data are well expressed with the parametrization√
22
2(1.93/Ei ) + 6.91/ Ei + (0.00) .

where the parameters a0 , a1 , and a2 are given in % and Ei in GeV, respectively. The energy resolution for
1 GeV positrons corresponds to 7.2%. The details of the analysis for the energy resolution are described
elsewhere [4].

§ 3. Position Resolution
The incident position of positrons on the calorimeter was reconstructed by the energy weighted
average of the position vectors xi of 9 modules as
xr ∝

9


Cj Ej xj ,

(7)

j=1

where the origin of the position vectors was the common center of a circumscribed sphere for front facesof the modules. The normalization was made in such a way that the length of the reconstructed position
vector should be the radius of the sphere (300 mm). Since the energy deposit to the central module wasmuch larger than that to the peripheral modules, the weight for the signal from the central module was
set to be smaller by using an extra factor Ci :⎧⎨ C
for the central module
0
Cj =
⎩ 1
for the peripheral modules(8)

The factor C0 was determined for each incident energy so that the mean of the difference between thereconstructed position and the incident position determined by BPM would be 0. The determined valuesof C0 are 0.01765±0.00002, 0.02684±0.00001, 0.02484±0.00001, 0.02123±0.00001, 0.02562±0.00001,
and 0.02473 ± 0.00001 for the incident energies of 300, 400, 500, 590, 670, and 800 MeV, respectively.
The difference distribution has a Gaussian shape whose mean is 0 by using the determined C0 . The x (y)position resolution is estimated with the width σx (σy ) which is obtained by ﬁtting a Gaussian function

18

Position resolution (mm)

20
18
16
14
12
10
8
6
4
2
0

x Component
0

0.2

0.4

y Component

0.6 0.8 0 0.2 0.4 0.6
Incident Energy E (GeV)

0.8

Fig.3. The position resolution as a function of the incident energy. The left and rightpanels show x and y components, respectively. The data are ﬁtted with the form√222
(a2 /Ei ) + a1 / Ei + (a0 ) .

to the difference distribution in x (y) direction. Figure 3 shows the position resolution as a function of
the incident energy. The position resolution σx and σy may also be represented with a similar function
to Eq. (5). The ﬁtted result are
⎧
1/2

2 
2
⎪
⎪
0.00
±
0.00
8.27
±
0.03
⎪
2
⎪ σx (Ei ) =√++ (6.18 ± 0.07)
and
⎪
⎨
Ei
Ei
1/2

2 
2
⎪
⎪
0.00
±
0.00
8.53
±
0.03
⎪
2
⎪
√
+
+ (5.68 ± 0.07),⎪ σy (Ei ) =
⎩
Ei
Ei

(9)

where the position resolution σx (σy ) and Ei are given in mm and GeV, respectively. The x and yposition resolutions for 1 GeV positrons correspond to 10.3 mm and 10.2 mm, respectively. The detailsof the analysis for the position resolution are described elsewhere [5].

Acknowledgment
We appreciate Dr. T. Matsumura for fruitful discussions on the energy and position resolutions for
the Lead/SciFi modules.

References[1]

T. Ishikawa, LNS Experiment #2536 (2005).

[2]

T. Ishikawa et al., Research Report of LNS, Tohoku University 39 (2006) 35.

[3]

T. Ishikawa, Internal GeV-γ analysis note No.43 (2007).

[4]

K. Mochizuki, Internal GeV-γ analysis note No.44 (2007).

[5]

K. Mochizuki, Internal GeV-γ analysis note No.46 (2007).

Research Report of Laboratory of Nuclear Seience, Tohoku University Vol. 40 (2007)

19(LNS Experiment : #2536, #2582)

LEPS Backward Gamma Detector Reassembled
T. Ishikawa, K. Mochizuki, K. Suzuki, Y. Okada, R. Hashimoto, J. Kasagi,
S. Kuwasaki, K. Nawa, Y. Onodera, M. Sato, H. Shimizu, and H. Yamazaki
Laboratory of Nuclear Science, Tohoku University, Sendai, 982-0826

A new electro-magnetic (EM) calorimeter complex FOREST covering a solid angle of about 4π sr
is under construction. It consists of three calorimeters: the EPS forward one made up of pure CsI
crystals, the middle one of lead scintillating ﬁber (Lead/SciFi) modules, and the backward one of lead
glass Čerenkov counters. We have reassembled the middle calorimeter, comprised of 252 Lead/SciFi
modules, which used to be the LEPS Backward Gamma detector system utilized in a LEPS experimentat SPring-8. A performance test for the gamma detector system has been made with a photon beam in
the GeV γ experimental hall. The π 0 peak is clearly observed in the γγ invariant mass distribution.

§ 1. Electro-Magnetic Calorimeter Complex FOREST
Nucleon resonances were experimentally studied via π 0 and η photo-production by using an electromagnetic (EM) calorimeter SCISSORS II in the GeV-γ experimental hall at Laboratory of Nuclear Science (LNS), Tohoku University. The π 0 and η mesons are identiﬁed as a peak at speciﬁc places in theγγ invariant mass distribution. It was difﬁcult, however, to detect all the γ’s coming from π 0 or η decay
since the solid angle of SCISSORS II was only 12.6% in total. In addition to that the process of multi-π
production is dominant in the GeV energy region. There is a huge background made up with wrong
combinations of γ’s, which do not form a peak of π 0 nor η in the γγ invariant mass distribution. To
suppress the background due to the wrong combinations, a large solid angle calorimeter is required sothat a fraction of undetected γ’s decreases.
A new EM calorimeter complex called Four-pi Omnidirectional Response Extended Spectrometer
Trio (FOREST) with a solid angle of about 4π sr has been planed [1]. It consists of three calorimeters.
The most forward region is covered with pure CsI crystals ‘SCISSORS III’ [2]. The detector systemcalled ‘Backward Gamma’ is placed at the central region. And a set of lead glass Čerenkov counters
covers the backward region. Figure 1 shows a schematic view of FOREST and a side view of Backward
Gamma. The Backward Gamma detector system covers 30◦ –100◦ in the polar angle and 0◦ –360◦ in theazimuthal angle, consisting of 252 Lead/SciFi modules. Each module has a 10◦ coverage both in thepolar and azimuthal angles. Backward Gamma was originally used at the Laser Electron Photon beamfacility at SPring-8 (LEPS).

20

a)

b)
Plastic
Scintillator
TargetLead/SciFi

Fig.1. a) Slant view of the new EM calorimeter complex FOREST. b) Side view of the LEPS
Backward Gamma detector. Backward Gamma consists of 252 Lead/SciFi modules. Each
module covers 10◦ both in the polar and azimuthal angles.

§ 2. Rebuilding of LEPS Backward Gamma Detector
The LEPS Backward Gamma system was reassembled from 9th to 23rd Nov. in 2006. The frameof Backward Gamma was rotated ﬁrst of all so that the plane corresponding to the polar angle of 90◦

Fig.2. LEPS Backward Gamma. The left panel shows a photo of the LEPS Backward Gamma
when the 90◦ –100◦ , 80◦ –90◦ , and 70◦ –80◦ Lead/SciFi modules were stacked. The rightpanel shows a photo of the constructed Backward Gamma together with SCISSORS III.

became horizontal. The largest Lead/SciFi modules covering a polar angle of 90◦ –100◦ were installed
into the frame at ﬁrst. Then 80◦ –90◦ modules were stacked on the 90◦ –100◦ ones. The 70◦ –80◦ and 60◦ –70◦ modules were installed in the same way. The left panel of Fig. 2 shows the middle stage of stacking
procedure. The 50◦ –60◦ , 40◦ –50◦ , and 30◦ –40◦ modules of the same azimuthal angle were stacked atonce so that the modules could not drop inside the frame during installation. The frame was rotated21back by 90◦ , after the installation of all Lead/SciFi modules was completed. Then the symmetry axis of
Backward Gamma was aligned to the axis of the GeV-γ beamline.

§ 3. Beam Test for Backward Gamma Detector
A beam test of Backward Gamma was performed from 5th to 7th June in 2007. A data acquisition
system for Backward Gamma was developed independently of that for the SCISSORS III. The energy
deposited in each module was digitized with a LeCroy 4300B Fast Encoding and Readout ADC (FERA)
in a CAMAC system. The data were collected and stored with a universal I/O (UIO) module [3] in a VME
system through a LeCroy 4301 FERA driver in the CAMAC system. The timing signals were measured
with CAEN V1190A TDC modules in the VME system. All the digitized data were ﬁnally accumulated
in a personal computer (PC) through the VME-bus. The trigger signals are made under the condition[TotalSigmaTagger] ⊗ [NBG ≥ 2],(1)

where TotalSigmaTagger stands for an OR signal of STB-Tagger II, and NBG ≥ 2 denotes the signal
which is generated when more than two modules are responded.
The energy calibration was made in such a way that the position of the peak corresponding to π 0events in the γγ invariant mass distribution should be at the π 0 mass. Figure 3b) shows the γγ invariant
mass distribution measured with Backward Gamma. The π 0 peak is clearly observed.

a)

}tl

b)

8000

|pv

7000

wj

jhthj

Counts

6000
5000
4000
3000
2000

{kj

1000

mlyh
k

0mlyhGGX]

0

100

200

300

400

γγ Invariant Mass (MeV)500

Fig.3. a) Dataﬂow of the data acquisition system for Backward Gamma. The digitized data ofenergies in FERA modules in a CAMAC system are collected in a UIO module through
FERA driver. Those of timing signals are obtained with TDC modules in a VME system.
b) The γγ invariant mass distribution measured with Backward Gamma. The π 0 peak isclearly observed.

Acknowledgment
We appreciate Dr. T. Yorita and Dr. T. Matsumura for many suggestions and advices in the reassembling process of Backward Gamma.

22

References[1]

T. Ishikawa: LNS Experiment #2536 (2005).

[2]

T. Ishikawa et al.: Research Report of LNS, Tohoku University 39 (2006) 35.

[3]

Y. Sugaya and M. Nomachi: Nucl. Instrum. Methods Phys. Res., Sect. A437 (1999) 68.

Research Report of Laboratory of Nuclear Seience, Tohoku University Vol. 40 (2007)

23(LNS Experiment : #2582)

Current Status of the Electro-Magnetic Calorimeter
SCISSORS III
T. Ishikawa, R. Hashimoto, J. Kasagi, S. Kuwasaki, K. Motiduki, K. Nawa,
Y. Okada, Y. Onodera, M. Sato, H. Shimizu, K. Suzuki, and H. Yamazaki
Laboratory of Nuclear Science, Tohoku University, Sendai, 982-0826

A new electro-magnetic calorimeter complex FOREST with a solid angle of about 4π in total is underconstruction. A forward calorimeter SCISSORS III, a part of FOREST, was constructed last year. We
have installed plastic scintillator hodoscopes in front of SCISSORS III. A beam test has been performed
for the forward detector assembly. The π 0 peak is clearly observed in the γγ invariant mass distribution.

§ 1. Plastic Scintillator Hodoscopes in Front of SCISSORS III
Nucleon resonances are experimentally studied via π 0 and η photo-production by using an electromagnetic (EM) calorimeter in the GeV-γ experimental hall [1] at Laboratory of Nuclear Science (LNS),
Tohoku University. These neutral mesons are identiﬁed in γγ invariant mass distributions. A new EM
calorimeter complex called FOREST (Four-pi Omnidirectional Response Extended Spectrometer Trio)with a solid angle of about 4π in total is under construction [2] to reduce a fraction of undetected γ’s.
It consists of three calorimeters. A forward one made up of pure CsI crystals ‘SCISSORS III’ was constructed last year [3]. Since an EM calorimeter itself cannot distinguish whether an incident particle isneutral or charged, a thin plastic scintillator hodoscope is usually placed in front of it. We have designed
and constructed a set of plastic scintillator hodoscopes named Spiral-shaped Particle Identiﬁcation Detector for Elementary Reactions (SPIDER), which is capable of determining the incident position of
charged particles precisely.
SPIDER consists of 3 layers, each of which is made up of 24 identical plastic scintillators. The side
curve of each plastic scintillator has a shape of spiral as depicted in Fig. 1. The spiral curve may be
represented asr = exp {b(θ + θ0 )} ,(1)

in the polar coordinate system, where r is a radius measured in mm, and b is a curvature parameter
being chosen to be 1.1. The inside and outside radii r range from 57 to 425(1 − 0.15 sin 15◦ ) mm and to425(1 + 0.35 sin 15◦ ) mm, respectively. The phase difference in θ between adjacent scintillators is 15◦ .
Two layers in SPIDER have different conﬁgurations in placing 24 spiral scintillators in a plane.
One of them is a left-handed layer and the other is right-handed. A pair of these left-handed and righthanded layers can determine the position of charged particles going through SPIDER. The third layer isplaced so as not to have inefﬁcient area taking place at the boundary region of spiral in each scintillator.

24yinsideθ

15oroutsidex

Fig.1. Spiral-shaped scintillators. The side curve of each plastic scintillator is represented asr = exp {b(θ + θ0 )} in the polar coordinate system. The phase difference between adjacent scintillators is 15◦ .

Figure 2 shows the schematic view and photo of SPIDER. The spiral-shaped scintillator is connected toa metal packaged photo-multiplier tube Hamamatsu R8900U through a twisted-type light guide.

Incident
Particle

Responded Plastic Scintillators
Incident Position
Fig.2. Schematic view and photo of SPIDER. The left panel illustrates how to reconstruct theincident position of charged particles. The right one shows the mounted SPIDER in frontof SCISSORS III.

§ 2. Beam Test of SCISSORS III
A beam test of SCISSORS III with SPIDER was performed from 3rd to 5th Jul. in 2007. A dataacquisition system for SCISSORS III was essentially the same as that for SCISSORS II. The energy andtiming of each crystal were digitized by ADC and TDC modules in two TRISTAN/KEK Online (TKO)systems [4]. The digitized data were collected and stored with Super Memory Partner (SMP) modules

25
in a VME system through Super Control Header (SCH) modules in the TKO systems. All the digitizeddata were ﬁnally accumulated in a personal computer (PC) through the VME-bus. Figure 3a) shows a
dataﬂow of the data acquisition system for SCISSORS III.
{rv

a)

1400
}tl
{rv

b)

1200

Counts

1000
jw|
wj

800
600
400

ztw

hkj {kj200
0

zjo hkj {kj0

50 100 150 200 250 300 350 400 450 500

γγ Invariant Mass (MeV)

Fig.3. a) Dataﬂow of the data acquisition system for SCISSORS III. The digitized data of energies and timings are collected from ADC’s and TDC’s in a TKO system through SCH and
SMP modules. b) The γγ invariant mass distribution measured with SCISSORS III. The
π 0 peak is clearly observed.

The trigger condition was described as([SigmaTagger i] ⊗ [NS3 ≥ 2]) ,(2)iwhere ⊗ means coincidence of signals. Channels of STB-Tagger II [5] were divided into 16 groups sothat the counting rate of each group should be the same, and an OR signal of each group is denoted by
SigmaTagger i (i = 1 . . . 16). Crystals of SCISSORS III were divided into 10 groups; a signal of eachgroup was generated when an analogue sum signal of the group exceeded the threshold. The NS3 ≥ 2stands for the signal in which more than two groups generate signals. A coincidence signal between
SigmaTagger i and NS3 ≥ 2 signals is required for taking data. Data can be taken with a higher
intensity tagged photon beam in this condition compared with the condition:
[SigmaTagger i] ⊗ [NS3 ≥ 2].

(3)i

A neutral cluster was selected as a γ particle, and the incident position is reconstructed by an energy
weighted average of the position vectors of the modules which joins the cluster. The energy calibration
is made so that the π 0 peaks in the γγ invariant mass distribution should be π 0 mass, where the events
are selected by the condition that both the cluster energies are larger than 200 MeV. Figure 3b) shows
the γγ invariant mass distribution measured with SCISSORS III. The π 0 peak is clearly observed.

26

References[1]

H. Shimizu et al., Research Report of LNS, Tohoku University 37 (2004) 13.

[2]

T. Ishikawa, LNS Experiment #2536 (2005).

[3]

T. Ishikawa et al., Research Report of LNS, Tohoku University 39 (2006) 35.

[4]

KEK Data Acquisition Development Working Group, KEK Report 85-10 (1985).

[5]

T. Nakabayashi et al., Research Report of LNS, Tohoku University 37 (2004) 17.

Research Report of Laboratory of Nuclear Seience, Tohoku University Vol. 40 (2007)

27

Development of a Multi-Purpose Logic Module with the
FPGA
K. Nanbu , T. Ishikawa , and H. Shimizu
Laboratory of Nuclear Science, Tohoku University, Sendai, 982-0826

We have developed a multi-purpose logic module (MPLM) with an FPGA. The internal circuit ofthis module can be modiﬁed easily with the FPGA. This kind of module enables trigger pulse processing
for nuclear science. As a ﬁrst step, the MPLM is used as an event tag generator in experiments with the
FOREST detector system.

§ 1. Introduction
The structure and production mechanism of hadrons have been experimentally investigated via
meson photo-production in Laboratory of Nuclear Science, Tohoku University. Nucleon resonances will
be studied intensively with an electro-magnetic calorimeter complex FOREST in the GeV-γ experimental
hall. Since the number of detectors in the FOREST is about 800, a set of logic modules for speciﬁed
purposes is expensive. Therefore, a multi-purpose logic module with a ﬁeld programmable gate array(FPGA) has been developed.

§ 2. Feature of FPGAAn FPGA is a semiconductor device which is programmable for any logic function by a designer. The
FPGA is usually slower than an application-speciﬁc integrated circuit (ASIC). Since the ASIC cannot be
modiﬁed after the design is completed, it is difﬁcult to handle an ASIC to implement a speciﬁed design
without bugs. On the other hand, the FPGA can be reconﬁgurable like software on a personal computer
after it is manufactured. It is easy to shorten designing time to obtain the speciﬁed logic function by atrial-and-error method.
The FPGA contains programmable logic components called logic blocks, and programmable interconnects. Logic blocks can be programmed to operate simple or combinatorial functions of basic logic
gates (AND, OR, XOR, ﬂip-ﬂops, and so on). The FPGA manufactured by Xilinx contains conﬁgurable
logic blocks (CLB), input/output blocks (IOB), block random access memories (RAM), multipliers, anddigital clock managers (DCM). The internal circuit of FPGA is constructed by connecting these elements.
The behavior of FPGA is usually deﬁned with a hardware description language (HDL). Conﬁguration data of logic blocks and interconnects which are ﬁtted to the actual FPGA architecture are generated
by a FPGA design software. The data are typically downloaded via a Joint Test Action Group (JTAG)28
link cable.

§ 3. Multi-Purpose Logic Module
We have developed a logic module called Multi-Purpose Logic Module (MPLM) with an FPGA. This
module is packaged in a single-width nuclear Instrumentation module (NIM) module. Figure 1 shows aphoto of the MPLM. The FPGA used is a Xilinx SPARTAN3, and contains 4320 ﬂip-ﬂops (FF), 256 Kbit
RAM, and 200,000 system gates.

Fig.1. The MPLM (A: Bin power, B: LEMO Connector, C: FPGA).

This newly developed module accepts NIM standard signals, through 16 input and output channels.
Since the FPGA does not accept the NIM signal, additional level converters between the NIM standard
and the Low Voltage Transistor-Transistor Logic Level (LVTTL) signals are employed. The propagation
delay from the input to the output is less than 10 ns, in which the conversion time from the NIM to
LVTTL signals is dominant.
Figure 2 shows the block diagram of the MPLM. The MPLM contains 16 inputs with NIM to LVTTL
converters, 16 outputs with LVTTL to NIM converters, a peripheral circuit for the conﬁguration of theFPGA, a clock signal, and 3 status light emitting diodes (LED). The clock signal is generated by a crystal
oscillator with a frequency of 33.33 MHz, and the frequency stability is better than 100 ppm. The FPGA
receives a clock signal through a built–in global buffer (GBUF). The power source for many devices in
the MPLM is provided through regulated power supplies as shown in Fig. 2. The MPLM supports the InSystem Programming (ISP) through the JTAG interface, and a FPGA conﬁguration system in a Platform
Flash Memory (PROM). This module detects failures of the clock signal and those of power system. An
RS-232C interface to a personal computer is optionally available. An operational ampliﬁer (OPAMP) is
operated with a higher frequency to shorten the leading time of the NIM standard signal (∼3 nsec). The
input impedance of the OPAMP is rather low for the FPGA. Nevertheless, the generated signal with the29

Fig.2. Block diagram of the MPLM.

Fig.3. Timing diagram of the 4bit binary counter implemented in the MPLM. The 1st and 4thchannels correspond to the lowest and most signiﬁcant bits, respectively.

OPAMP meets the NIM standard although some reﬂection is observed in a pulse of the signal due tothe impedance mismatch. Since this module is constructed on a 4 layer printed-circuit board (PCB), theimpedance of the power system is reduced, which results in the noise level suppressed, in addition thehigh frequency operation allows the use of surface-mount components.
As a ﬁrst step, this module is used as an event tag generator in experiments. A data taking system
for FOREST is divided into several subsystems to collect digitized data with a short dead time. The

30
event tag is important to check event consistency whether digitized data collected by these subsystems
belong to the same event or not. When the generator receives a trigger accept signal, a 4 bit associatedevent tag is generated. Figure 3 shows the operation of a 4 bit binary counter in the MPLM.

§ 4. Conclusion
A Multi-purpose Logic Module has been developed. This kind of module is necessary to handle
digitized data efﬁciently under complicated trigger conditions.

Research Report of Laboratory of Nuclear Seience, Tohoku University Vol. 40 (2007)

31(LNS Experiment : #2581)

Radiation Hardness Test of GaN Diode for Irradiation withHigh Energy Electron Beam
S. Narita1 , Y. Yamaguchi1 , Y. Chiba1 , H. Yuki2 , F. Hinode2 , and J. Kasagi2
1

Department of Electrical and Electronic Engineering, Iwate University, Morioka, 020-8551
2

Laboratory of Nuclear Science, Tohoku University, Sendai, 982-0826

The GaN is expected to be a new material for the particle detector with radiation hardness, as
substitution of Si. We have developed the GaN Schottky diode which is a prototype of the ionizing detector. In this study we performed the test of radiation tolerance for the diode we fabricated, irradiating ahigh energy electron beam. As the result, we found that the performance of the diode was not changed
signiﬁcantly even after irradiating 1016 /cm2 electrons.

§ 1. Introduction
In high-energy collider experiments, the beam luminosity has been increasing, and a semiconductor
detector with radiation hardness is strongly desired in the current and future experiments. Several
semiconductor materials have been investigated for developing new particle detectors as the substitutionof Si [1, 2]. Among them, a wide-gap nitride semiconductor, especially gallium nitride (GaN), is one ofthe possible candidates. Recently, GaN devices have been widely used (e.g., light emitting device) andthe technology to produce high quality substrate has been improved remarkably, so that development of
the particle detector with GaN is now promising [3].
We have been developing the GaN based particle detector and successfully fabricated the GaN
Schottky diode which has high quality in electrical and optical characteristics. Now it enables us torealize the GaN particle detector. In this study, we irradiated the diodes with high energy electrons anddiscussed the radiation hardness of GaN material.

§ 2. Experiment
2.1 GaN diode sample
The Schottky barrier diodes used in this study were fabricated with heterostructure substrate produced by Powdec K.K. growing an epitaxial GaN layer on n-type SiC substrate. Most of the current GaN
devices are based on GaN on Sapphire substrate. For the Schottky diode device using GaN/Sapphire
substrate, both Schottky and Ohmic contacts have to be made on the same surface because Sapphire
is insulator. However, the diode with such a structure is not preferred to use for the particle detector
because the device design is complicated and its sensitive area is limited. On the other hand, the diodewith GaN/SiC substrate can be designed more simply due to the electric conductivity of SiC. The Ohmic
contact can be put on the SiC side. The diode structure is shown in Fig.1.

32

Au padSchottky contact

820 μmNi /Auu-GaN
500 μm

n-SiC

120μm

Ohmic contact
Ti /AuFig.1. GaN diode structure.

The chip size of the diode was 0.5×0.5 mm2 , and the thickness of the GaN and SiC layers were∼900 and ∼280 nm, respectively. The Ti/Au Ohmic contact was deposited on to the SiC and the Schottky Ni/Au electrode was put onto the GaN layer. For the irradiation test, the diode was placed onto
the metal package. The current-voltage (I-V) characteristics of the diodes were measured by the ultrahigh resistance meter (ADVANTEST R8340). The leakage current was well suppressed (∼10 nA/cm2 )and the breakdown voltage was typically above 20V. These performances were comparably good to thepresent GaN diode. We also investigated the photo-conductivity to the UV light, and it showed a good
performance as the photo diode. Actually, the thickness of the sensitive layer was too thin to evaluate
the performance for the charged particle (even for, e.g., α particles), for now.
The I-V characteristics were measured before and after irradiation in order to determine the effectsof the incident electrons.
2.2 Electron beam irradiation
Beam irradiation was carried out at Laboratory of Nuclear Science, Tohoku University (LNS), using
a 150 MeV pulsed electron beam. The beam current was measured by the SEM placed at the downstreamof the target diodes. The conversion factor from the SEM current to the beam current was calibrated
in advance of the experiment, which has about 30% uncertainties. The mean beam current value inthis experiment was found to be 2.5 μA. We assumed that the beam condition was stable during theirradiation, then the current measurement was employed just once in prior to the irradiation. In thisexperiment, we prepared several diodes and irradiated them with electrons with various ﬂuences. During the irradiation, the target diodes were not applied voltage, then the output currents from the diodewere not monitored.
The beam proﬁle was measured by the radio-activity of aluminum foil irradiated with the electron
beam with the same conditions in the irradiation to the diodes. After irradiating the foil, the activity ofthe segmented area of the foil was measured by a Ge detector. The proﬁles along X and Y axes with the
ﬁtted Gaussian curves are shown in Fig.2. The electron ﬂuences on the diode were obtained considering
the mean current of the beam and these proﬁles. The ﬂuence for each sample is shown in Table 2.2. The
errors in the list were from the uncertainties of the SEM calibration data.

Relative Intensity

33

1

1

0.8

0.8

0.6

0.6

0.4

0.4

0.2

0.2

0

-10

0
10
Beam X (cm)

0

-10

0
10
Beam Y (cm)Fig.2. Beam proﬁle ﬁtted with the Gaussian. (left:X, right:Y). The ﬁtted curves represent f (x) =1.01e(x+0.98)2
6.442

for X-axis and f (y) = 1.08e(y−1.24)2
5.902

for Y-axis, respectively.

Table 1. Calculated electron ﬂuences for each sample.
Sample 1
Sample 2
Sample 3
Sample 4

Electron ﬂuence [/cm2 ]2.2 ± 0.7 × 1014
2.2 ± 0.7 × 1015
1.8 ± 0.4 × 1016
3.4 ± 1.0 × 1016

§ 3. Results and Discussion
Figure 3 shows the I-V curves before and after irradiation for each ﬂuence. No signiﬁcant increaseof leakage currents was seen even with the electron ﬂuences above 1016 /cm2 . The break down voltage
was not changed clearly. These results would prove the radiation hardness of the GaN.
The degradation of the semiconductor detector is strongly dependent on the energy loss of particles
irradiated in both non-ionizing (atomic displacement) and ionizing (form of electron-hole pair) processes
in the material. The non-ionizing energy loss of a 150 MeV electron is estimated to be 0.1 keV cm2
g−1 [4], and this is smaller than that of other charged particles and a neutron. Besides the type of theparticles, we should consider that the thickness of the diode used in this experiment was just ∼ 1μm. The
particle detectors used practically have much thicker structure, so that non-ionizing and ionizing effects
are supposed to increase in such detectors. Therefore we still need to perform the irradiation test using
heavy charged particles such as protons or α particles to discuss precisely the radiation hardness of the
GaN material. Furthermore, we should repeat the test with changing the experimental conditions since
the damage effects depend on various parameters (e.g., with/without applying the voltage, temperature,device structure, and so on).

34

before irradiation

after irradiation

-2

10
-4
10
-6
10
-8
10
-10
10

Sample-1

-15

-10

-5

0

-15

-10

-5

0

-10

-5

0

-15

-10

-5

0

-10

-5

0

-15

-10

-5

0

-10

-5

0

-15

-10

-5

0

2

Current density [A/cm ]

-2

10
-4
10
-6
10
-8
10
-10
10

Sample-2

-15
-2

10
-4
10
-6
10
-8
10
-10
10

Sample-3

-15
-2

10
-4
10
-6
10
-8
10
-10
10

Sample-4-15Bias voltage [V]Fig.3. Current-Voltage characteristics for the sample before and after electron beam irradiation.

§ 4. Summary
We have evaluated the tolerance of the GaN material for the radiation damage irradiating withhigh energy electron beam. The performance was not signiﬁcantly changed after irradiating 1016 /cm2
electrons. The GaN might be a promising candidate for the material of future particle detectors. We
should keep investigating the performance under various conditions and ensure the advantages.

35

Acknowledgment
We acknowledge technical and scientiﬁc staffs of the LNS. This work was supported by Grant-in-Aid
for Young Scientists (B) by the Ministry of Education, Culture, Sports, Science and Technology (MEXT).

References[1]

M. Moll: Nucl. Instrum. Methods Phys. Res., Sect. A 511 (2003) 97.

[2]

J. Grant etal .: Nucl. Instrum. Methods Phys. Res., Sect. A 546 (2005) 213.

[3]

J. Vaitkus etal .:Nucl. Instrum. Methods Phys. Res., Sect. A 509 (2003) 60.

[4]

A. Holmes-Siedle and L. Adams: “Handbook of Radiation Effects” (Oxford University Press, 2001).

核理研研究報告36

第 40 巻2007(LNS Experiment : #2587)

J-PARC 実験用ゲルマニウム検出器の波形読み出し法の開発
細見健二 1 , 鵜養美冬 2 , 大谷友和 1 , 小池武志 1 , 馬越 1 , 三森雅弘 1 , 三輪浩司 1 ,白鳥昂太郎 1 , 田村裕和 1
1 東北大学大学院理学研究科 (980-8578 仙台市青葉区荒巻字青葉)

2 東北大学サイクロトロン・ラジオアイソトープセンター (980-8578 仙台市青葉区荒巻字青葉)

Development of Waveform Readout System for Germanium
Detectors at J-PARC
K. Hosomi1 , M. Ukai2 , T. Otani1 , T. Koike1 , Y. Ma1 , M. Mimori1 , K. Miwa1 ,K. Shirotori1 , and H. Tamura1
1
2

Department of Physics, Tohoku University, Sendai, 980-8578

Cyclotron and Radioisotope Center, Tohoku University, Sendai, 980-8578

The waveform of signals from a germanium detector was measured by a Flash ADC under the highcounting condition by a positron beam at LNS. Even if a baseline is shifted after preamp reset, theoriginal energy was obtained by analyzing the waveform. The effectiveness of the wavefrom readout for
J-PARC experiments was shown.

§ 1 . はじめに
現在、我々のグループは J-PARC においてハイパー核ガンマ線分光実験 [1]を行うため、新型のゲルマ
ニウム検出器アレイ「Hyperball-J」を建設中である。J-PARC で実験を行う際、旧 Hyperball 用の読み出し方法を用いた場合には、ビーム強度の増加にともなう不感時間の増加から 2 MHz 以上のビーム強度ではデータ収集が行えないと予想される。第 1 表に J-PARC で予想される実験条件を示した。旧 Hyperball
用の読み出し方法はプリアンプ、整形アンプ、パルス波高型 ADC という流れでゲルマニウム検出器に入ったエネルギー情報を波高情報に変換して読み出す方式になっており、不感時間を生じる要因は以下の２つである。１つ目はプリアンプのリセットである。運動量が GeV オーダーの中間子ビームを使って実験を行う
ため、散乱ビームなどによる高いエネルギー付与率に耐えられるよう、低増幅率のトランジスター・リセッ
ト型のプリアンプを使っている。しかし、プリアンプのリセット時には、その後の数 10 μ 秒間は整形アンプのベースラインが変動してしまい正しい波高を得ることができず不感時間を生じる。もう１つは波形同士のパイルアップである。この場合もリセット直後と同様に正しい波高情報を得ることができず不感時間となる。
この問題を解決するため、Hyperball-J ではフラッシュADC を用いた波形読み出し法に変更する予定である。これは、整形アンプ出力を波形情報のまま記録し、オフライン解析によりリセット直後のベースライ
ン補正とパイルアップの分離を行おうというものである。本来ならプリアンプ出力を直接フラッシュADC

37で読み出すべきなのだが、フラッシュADC の性能によりエネルギー分解能が制限∗ されてしまうため、現段階では整形アンプ出力を読み出すこととする。
第 1表

ビーム強度
カウントレート
エネルギー付与率
不感時間§2 . 実ハイパー核ガンマ線分光実験の条件。

K6 (KEK) 実測値
2 MHz (π + )50 kHz〜0.5 TeV/s〜50 %K1.8 (J-PARC) 予想値〜10 MHz (K − )〜250 kHz〜2.5Te V/s
100 %

験

本実験は、プリアンプのリセット直後に検出したガンマ線イベントに対して、波形解析のアルゴリズム開発とその補正効果の検証を目的として行われた。実験は、10 kHz の陽電子ビームを直接ゲルマニウム検出器に照射し、エネルギー付与率を 0.4 TeV/s (リセット率 2〜3 kHz) としてハイパー核実験の状況を再現したうえで、60 Co 線源からのガンマ線を測定した。測定に用いた 60 Co 線源はプラスチックシンチレータ(＋光電子増倍管) の中に埋め込まれており、ゲルマニウム検出器と組み合わせてベータ・ガンマ・コイン
シデンスをとることで効率よくリセット直後のガンマ線イベントにトリガーをかけてデータ収集することに成功した。また比較のため、整形アンプ出力を２つに分けフラッシュADC とパルス波高型 ADC で同時に同じイベントを記録した。

§ 3 . 解析と考察
リセット直後の整形アンプ出力のベースライン変動の大きさはイベントごとに異なっていることがフラッ
シュADC の波形データから分かった。このため、イベントごとにベースライン部分を抜き出し、2 次関数
でフィッティングして正しいベースライン位置を見積もった上で波高を読み取る解析方法を考えた。ベース
ライン部分のみを抜き出すアルゴリズムは、波形データを微分してその微係数がゼロに近くなるところを選択する方式をとっている。第 1 図に解析で得られた 60 Co のガンマ線スペクトルを示す。波線で表示されているのはパルス波高型 ADC で測定した場合で、リセット直後のベースライン変動によって正しい波高が読めずピークが広がってしまっているのが確認できる。実線で表示されているのは同じイベントをフラッシュ

ADC で測定し、ベースラインの補正を行った場合である。2 つを見比べると、補正によってベースライン
変動の影響を改善できていることが分かる。現在の解析では、リセット率が 2 MHz の条件下でゲルマニウ
ム検出器の信号を 3.1 keV(半値幅 @ 1 MeV) のエネルギー分解能で読み出すこができている。パルス波
高型 ADC ではエネルギー分解能は 3.7 KeV であり、補正によってエネルギー分解能は改善している。また、相対検出効率をピークの面積比で見積もると、パルス波高型 ADC を使った場合にくらべてフラッシュ

ADC を使った読み出しの方がリセット直後のイベントに対して約 1.5 倍に増えていることが分かった。以上の結果より、旧 Hyperball 用の読み出し方法では正しく読み出せなかった プリアンプ・リセット直後の∗プリアンプ出力を直接読み出すのに必要なフラッシュADC の性能を見積もるとダイナミックレンジが 10 V、有効ビット数が 19 ビット、サンプリング周期が 100 MHz となる。

38

イベントに対してフラッシュADC を用いた読み出し方法ではオフライン解析で補正することで正しく読み出せることが分かり、波形読み出しの有効性を示すことができたといえる。

第1図

プリアンプ・リセット直後のベースラインが変動しているイベントに対してパルス波高型
ADC とフラッシュADC ＋波形解析で読み出した 60 Co 1.33MeV ピークのエネルギース
ペクトルの比較。

§ 4 . まとめと今後の課題
ゲルマニウム検出器のプリアンプ・リセット直後のベースラインが変動している間に計測されたガンマ線イベントに対してフラッシュADC を使った波形読み出しを行い、得られたデータを元に補正用のアルゴ
リズムを開発した。オフラインでベースラインのフィッティング解析を行った結果、ベースラインが変動していても補正することで 3.1 keV(半値幅 @ 1 MeV) エネルギー情報を読み出すことに成功した。今後の課
題は、開発したベースライン補正アルゴリズムの再検討とパイルアップに対する解析アルゴリズムの開発で
ある。

参
[1]

考

文

献

H. Tamura et al.: J-PARC proposal E13, ”Gamma-ray spectroscopy of light hypernuclei”(2006).

Ԇȅ3BEJPDIFNJTUS Z

核理研研究報告

第 40 巻2007

39(LNS Experiment : #2574, #2585)

3 種ユークライト隕石（Dhofar 007，Juvinas，Stannern）の希ガス
および全岩化学組成に関する研究
竹田光世, 大浦泰嗣, 海老原充
首都大学東京大学院理工学研究科 （192-0397 東京都八王子市南大沢 1-1）

Noble Gas and Bulk Chemistry Study of Three Eucrites
Juvinas, Stannern and Dhofar 007
M. Takeda , Y. Oura , and M. Ebihara
Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1
Minami-Ohsawa, Hachioji, Tokyo 192-0372
We performed bulk chemical and noble gas analyses of three eucrite meteorites, Juvinas, Stannern
and Dhofar 007 (Dho 007) for their single specimens and estimated 244 Pu-Xe age. Juvinas and Stannern
are brecciated noncumulate eucrites. Dho 007 is an anomalous cumulate eucrite, which is suggested
to be a possible relationship with mesosiderites. We present here new data of bulk chemical composition and chronological information for Dho 007 in addition to these for the other eucrites, Juvinas andStannern.

§ 1 . はじめにユークライト隕石は小惑星の地殻由来の物質であると考えられている隕石である。ユークライト隕石母天体である小惑星は火成活動を経て分化したと考えられており、この小惑星由来の隕石の分析は，惑星進化過程の解明に繋がると考えられている．隕石の初期進化過程を推測する方法の一つとして、放射性核種を利用した年代測定法が挙げられる。中でも、消滅核種（太陽系の年齢〜45.6 億年と比較して短い半減期を持つため現在は存在しない核種）244 Pu（半減期〜8100 万年）とその自発核分裂片である Xe を利用した 244 Pu-Xe
相対年代法はユークライト隕石の初期形成過程を考察する上で非常に有力な手段である。

1999 年にオマーン砂漠で発見された Dhofar 007（Dho 007）はその鉱物および化学組成は集積岩ユーク
ライトの範囲に入るが、金属片を含み Yamaguchi et al. [1] によってユークライトとは異なる隕石グループの一つであるメソシデライトとの関連性が示唆された隕石である。これまでにこの Dho 007 に関しての形成年代は得られていない。そこで本研究では Dho 007 および、非集積岩ユークライトである Juvinas、

Stannern について化学組成と希ガス同位体組成を求め、この隕石の Angra dos Reis（207 Pb-206 Pb 年代
4.5578±0.0004）[2]に対する 244 Pu-Xe 相対年代を算出することを試みた。

40§2 . 実験

東京大学地殻化学実験施設より提供された３つのユークライト隕石（Juvinas, Stannern, Dho 007）を試料として用いた。試料はそれぞれ希ガス同位体分析用（125〜190 mg）と全岩化学組成分析用（180〜

265 mg）の二つに分け、希ガス同位体分析は東京大学地殻化学実験施設の希ガス質量分析装置（VG-5400、
MS-II）を用いて行った。全岩化学組成は即発 γ 線分析（PGA）、機器中性子放射化分析（INAA）、機器
光量子放射化分析（IPAA）の３種の放射化分析法により求めた。さらに，ここでは詳細を省略するが Ba、希土類元素、Th、U 濃度を誘導結合プラズマ質量分析により求めた。放射化分析の概略を以下に示す。

PGA：全岩化学分析用の試料（粗粒状）の全量を四フッ化エチレン六フッ化プロピレンフィルム封入し、日本原子力研究開発機構（JAEA）JRR-3M 実験ホール内の即発 γ 線分析装置にて約３時間、中性子照射・測定を行った。

INAA：PGA 後の試料をメノウ乳鉢で粉末化し、一部（20 から 30 mg）を高純度ポリエチレンフィル
ムに封入した。これらの試料に対し、JAEA の JRR-3、PN-3 にて 10 秒間中性子照射を行い、その後速やかに γ 線を測定した。またこの試料を約 2ヶ月冷却し、JAEA の JRR-4、T-pipe にて 20 分間中性子照射
した後、適当な冷却時間を置いて、首都大学東京 RI 研究施設にて γ 線測定を複数回行った。

IPAA：PGA 後粉末化した試料の一部（約 30 mg）を Al 箔に包み、直径 10 mm の円板状に整形した。
比較標準試料である岩石標準試料 JB-1、Allende 隕石も同様に調整した。これをフラックス補正の為の金箔と共に石英管に常圧封入し、東北大学原子核理学研究施設電子線形加速器にて最大エネルギー 30 MeV の制動放射で 30 分間照射し、ただちに γ 線測定を行った。更に測定後の試料を約 4 時間半照射し、適当な冷却時間を置いて、首都大学東京 RI 研究施設にて γ 線測定を複数回行った。

§ 3 . 結果と考察
３つの放射化分析の組み合わせにより主要・微量元素が、また ICP-MS により Ba、希土類元素、Th、Uが定量できた。放射化分析による定量結果を第１表にまとめた。Juvinas、Stannern ではすべての元素で、Kitts and Lodders (1998) [3]の編纂値の範囲に入った。 しかし Dho 007 では、得られた結果が Yamaguchi
et al.. (2006) の値と大きく異なり、特に希土類元素では文献値の 2∼3 倍の濃度を示し、希土類元素存在度
パターンも異なる傾向を示した。Dho 007 は発見された総量がおよそ 21 kg と大きく、 Yamaguchi et al.

(2006) とは試料の提供源が異なる。このことから、Dho 007 の組成の違いは隕石の部位の違いによる不均一が原因であると考えられるが、本研究では鉱物学的観察等は行っておらず、今後の課題である。
計算法の詳細は省略するが、この結果と希ガス同位体分析の結果を用いて 244 Pu-Xe 相対年代を算出したところ、Juvinas（-24±5 Ma）、Stannern（-103±30 Ma）については文献値（Juvinas：-10±23 Ma、Stannern：-124±13 Ma）[4]と良く一致する年代が得られたが、Dho 007 では年代値として妥当な値を得ることができなかった。この原因として、Dho 007 が地球上での風化を受けている可能性が挙げられる。
244 Pu-Xe 相対年代を求めるには隕石の Ba、軽希土類元素（LREE；La + Ce + Nd）の比と U の含有量が必要である [3]。しかし Dho 007 は砂漠隕石であり、これらの元素濃度が地球上での風化の影響により本来の濃度から変化した可能性があるので、これを考慮して年代を算出する必要がある。横軸に Yb、縦軸にSr や Ba などの風化の影響を受けやすい元素をとって文献値 [5, 6]と共にプロットすると、Dho 007 は他のユークライト隕石で見られる元素の相関から明らかに外れたところにプロットされる（第１図）。これよ41

即発 γ 線分析、機器中性子放射化分析、機器光量子放射化分析によるユークライト隕石の定量結果。
JuvinasStannern
Dhofar007
this work
lit.∗
this work
this worklit.∗%
22.6 ± 0.5
22.97 ± 0.3
23.3 ± 0.5
23.00 ± 0.45
22.9 ± 0.5%
0.437 ± 0.001 0.3713 ± 0.0231 0.576 ± 0.001 0.586 ± 0.0272 0.219 ± 0.001%
6.87 ± 0.06
6.93 ± 0.20
6.20 ± 0.04
6.47 ± 0.37
5.80 ± 0.04
ppm
1940 ± 31783 ± 369
2119 ± 3
2081 ± 330
2854 ± 5%14.48 ± 0.04
13.9 ± 0.9
14.7 ± 0.0
14.1 ± 1.0
13.3 ± 0.0%
0.435 ± 0.010
0.404 ± 0.020
0.434 ± 0.011
0.392 ± 0.361
0.409 ± 0.010%
3.89 ± 0.33
4.22 ± 0.10
4.28 ± 0.40
4.23 ± 0.24
6.61 ± 0.49%
6.50 ± 0.02
7.66 ± 0.40
6.89 ± 0.02
7.54 ± 0.31
5.95 ± 0.02%
0.300 ± 0.001
0.320 ± 0.028
0.412 ± 0.001
0.403 ± 0.046
0.278 ± 0.001%
0.026 ± 0.005 0.0328 ± 0.0064 0.062 ± 0.008 0.0646 ± 0.0078 0.033 ± 0.005
ppm
0.90 ± 0.11
0.965 ± 0.474
1.17 ± 0.14
3.390 ± 3.361
0.987 ± 0.136%
0.705 ± 0.044
0.15 ± 0.10
0.52 ± 0.05
0.19 ± 0.12
2.76 ± 0.07
ppm
n. d.
28.50 ± 14.80
n. d.
34.5
305 ± 19ppm
59.3 ± 3.8
85 ± 1654.5 ± 3.7
77.0 ± 12.0
86.9 ± 4.0
ppm 31.13 ± 0.07
28 ± 1.6
31.05 ± 0.08
31.2 ± 0.85
24.81 ± 0.06
ppm
6.58 ± 0.08
4.7 ± 0.9
4.89 ± 0.07
6.6 ± 3.4
50.5 ± 0.2%
n. d.
4 ± 3.4
n. d.
7 ± 2.8
0.115 ± 0.001
ppm
70.2 ± 3.0
74.9 ± 5.2
88.0 ± 1.3
88.8 ± 6.0
127 ± 2
ppm
19.5 ± 0.7
16.5 ± 0.7
30.3 ± 1.0
27 ± 1.2
8.06 ± 0.48
ppm
45.1 ± 0.7
44.9 ± 1.6
93.8 ± 0.9
88 ± 1.1
21.03 ± 0.53
ppm
2.95 ± 0.04
2.582 ± 0.238
5.13 ± 0.06
5.166 ± 0.320
1.14 ± 0.03
ppm
8.92 ± 0.45
6.934 ± 0.563
13.9 ± 0.6
13.344 ± 0.694
2.21 ± 0.49
ppm
1.90 ± 0.01
1.623 ± 0.128
3.13 ± 0.01
3.227 ± 0.175
0.632 ± 0.006
ppm
0.71 ± 0.05
0.624 ± 0.036
0.84 ± 0.07
0.808 ± 0.047
0.420 ± 0.022
ppm
1.88 ± 0.07
1.602 ± 0.188
2.96 ± 0.10
2.663 ± 0.314
0.899 ± 0.046
ppm
0.27 ± 0.01
0.255 ± 0.024
0.41 ± 0.02
0.408 ± 0.028
0.128 ± 0.009
ppb
n. d.
0.096 ± 0.08
n. d.
0.12 ± 0.01
54.9 ± 1.4
ppb
n. d.
4.3 ± 3.4
n. d.
6.85 ± 9.43
19.9 ± 1.2

第 1表

Si
Ti
Al
Cr
Fe
Mn
Mg
Ca
Na
K
B
S
Cl
V
Sc
Co
Ni
Sr
Y
Zr
La
Ce
Sm
Eu
Yb
Lu
Ir
Au
∗

Kitts and Lodders (1998). ∗∗ Yamaguchi et al. (2006).

第1図集積岩ユークライト、非集積岩ユークライトにおける元素濃度の相関。影の部分は砂漠隕石を除いた隕石の取る値の範囲を、破線および実線はそれぞれ集積岩ユークライト、非集積岩ユークライトに対する回帰曲線を示す。(a)Yb 濃度と Sr 濃度の相関。(b)Yb 濃度とU 濃度の相関。

lit. ∗∗
21.6
0.123
6.67
3052
12.2
0.403
5.67
8.22
0.257
0.0241
0.465
81.6
21.61
59.8
0.0929

0.386
0.908
0.261
0.330
0.427
0.067
49
9.2

42

り、Dho 007 では Sr、Ba、LREE、U で風化の影響を受けていることが判った。さらに，Yamaguchi etal. (2006) の値からも外れた所にプロットされていることが分かる。これは前述の通り試料部位の差によると考えられ、隕石の部位によって風化の度合いも異なることを示している。以上から、U 含有量は第１図(b) の U/Yb から、また Ba/LREE は Ba と LREE の相関（第２図）から見積もった値を用い、Dho 007の 244 Pu-Xe 相対年代を算出したところ、-10±2 Ma という値を得ることができた。

第2図

第２図 集積岩ユークライト、非集積岩ユークライトにおける Ba と LREE（La + Ce +Nd）の相関。影および破線、実線の示すものは第１図に同じ。

他のユークライト隕石の年代 [3]と比較した結果、この隕石がユークライト隕石の中でも、かなり古い年
代を示すことが判った。この Dho 007 については今後用いた部位について鉱物学的観察を行い、その結果と合わせてこの年代値の意味を考える必要がある。

§4 . ま と め
特異な集積岩ユークライトである Dho 007 を含めた３つのユークライト隕石について、放射化分析と質量分析により、希ガス同位体組成、全岩化学組成を求めた。この結果からこれら 3 つの隕石について 244 Pu-Xe
相対年代を算出した。Dho 007 では風化の影響を考慮して年代を得たが、この結果からこの隕石がユーク
ライト隕石の中で、かなり古い年代を持つものであることが判った。
謝辞
本研究を行うにあたり良質な電子ビームを供給していただいた東北大学原子核理学研究施設マシングルー
プの方々と、試料照射ならびに放射線測定でお世話になった大槻勤准教授と結城秀行博士に深く感謝する。

参

考

文

献

[1]

Yamaguchi et al.: Meteorit. Planet. Sci. 41 (2006) 863.

[2]

Lugmair and Galer: Geochim. Cosmochim. Acta 56 (1992) 1673.

[3]

Kitts and Lodders: Meteorit. Planet. Sci. 33 (Suppl.) (2000) A197.

43

[4]

Miura et al.: Geochim. Cosmochim. Acta 62 (1998) 2369.

[5]

Barrat et al.: Meteorit. Planet. Sci. 35 (2000) 1087.

[6]

Barrat et al.: Geochim. Cosmochim. Acta 67 (2003) 3959.

ԇȅ-JTUPG1VCMJDBUJPOResearch Report of Laboratory of Nuclear Science, Tohoku University Vol. 40 (2007)

ĵĶȪ2006.1ȡ2006.12ȫ
List of PublicationȪა໲ςΑΠȫPapers Published in Refereed Journals
Photoproduction ofĥ-mesons off C and Cu Nuclei for Photon Energies below 1.1 GeV.
T. Kinoshita, H. Yamazaki, H. Fukasawa, K. Hirota, 1, T. Ishikawa, J. Kasagi, A. Kato,
T. Katsuyama, K. Kino. Miyahara, T. Nakabayashi, K. Nawa, K. Okamura, Y. Saitoh,
K. Satou, M. Sengoku, H. Shimizu, K. Suzuki, S. Suzuki, T. Terasawa, H. Kanda,
K. Maeda, T. Takahashi, Y. Aruga, T. Fujinoya, A. Iijima, M. Itaya, Y. Ito, T. Iwata, H. Kato,
T. Kawamura, T. Michigami, M. Moriya, T. Sasaki, Y. Tajima, S. Takita, T. Noma,
M. Yamamoto, H.Y. Yoshida, Y. Yoshida, O. Konno, T. Maruyama and T. Yorita
Phys. Lett. B639 (2006) 429 -435.
Photoproduction ofĥMesons off Protons for Eġƿ 1.15 GeV.
T. Nakabayashi, H. Fukasawa, R. Hashimoto, T. Ishikawa, T. Iwata, H. Kanda, J. Kasagi,
T. Kinoshita, K. Maeda, F. Miyahara, K. Nawa, T. Nomura, Shimizu, T. Shishido,
K. Suzuki, Y. Tajima, T. Takahashi, H. Ueno, H. Yamazaki, and H.Y. Yoshida
Phys. Rev. C74 (2006) 035202 (1-7).
Photo-Production of Neutral Kaons on C-12 in the Threshold Region.
T. Watanabe, P. Bydžovský, K. Dobashi, S. Endo, Y. Fujii, O. Hashimoto, T. Ishikawa,
K. Itoh, H. Kanda, M. Katoh, T. Kinoshita, O. Konno, K. Maeda, A. Matsumura,
F. Miyahara, H. Miyase, T. Miyoshi, K. Mizunuma, Y. Miura, S.N. Nakamura, H. Nomura,Y. Okayasu, T. Osaka, M. Oyamada, A. Sasaki, T. Satoh, H. Shimizu, M. Sotona,
T. Takahashi, T. Tamae, H. Tamura, T. Terasawa, H. Tsubota, K. Tsukada, M. Ukai,
M. Wakamatsu, H. Yamauchi and H. Yamazaki
Physics Letters B651 (2007) 269-274.
Measurement of E2-E0 Strength in the Isovector Giant Resonance (GQR-GMR) Region of 28Si Nuclei
through the (e, e'n) Reaction.
K. Kino, T. Saito, T. Nakagawa, T. Tamae, I. Nishikawa, Y. Asano, H. Toda, M. Watabe,
T. Nakagawa, H. Tsubota, K. Takahashi, M. Utoyama, M. Higuchi, Y. Matsuura, H. Ueno,
and T. Suzuki
Phys. Rev. C73 (2006) 034614 (1-6).
Isovector Quadrupole Resonance in 13C(ġ, n) Reaction.
K. Maeda, S. Ito, H. Itoh, O. Konno, H. Matsuyama, T. Murakami, T. Sasaki, T. Suda,
M. Takeya, and T. Terasawa
J. Phys. Soc. Japan 75 (2006) 034201 (1-8).
200-MeV Bremsstrahlung Tagged Photon Beams at Sendai.
K. Hirose, M. Chiba, M. Inoue, H. Kanda, R. Kimura, K. Kino, Y. Kobayashi, O. Konnno,
K. Maeda, H. Miyase, A. Miyamoto, T. Otsuki, A. Saito, T. Suda, K. Takahashi, T. Tamae,
Y. Terasaki, T. Terasawa, H. Tsubota, T. Tsuruta, M. Utoyama, H. Yuuki, Y. Yamaguchi,ĵķand H. Yamazaki
Nucl. Instrm. and Meth. A564 (2006) 100-107.
ơ n → K + ĘReaction at E ġ = 1.5 - 2.4
Differential Cross Section and Photon-Beam Asymmetry for the ġ
GeV.
H. Kohri, D.S. Ahn, J.K. Ahn, H. Akimune, Y. Asano, W.C. Chang, S. Date', H. Ejiri,
S. Fukui, H. Fujimura, M. Fujiwara, S. Hasegawa, K. Hicks, T. Hotta, K. Imai,
T. Ishikawa, T. Iwata, H. Kawai, Z.Y. Kim, K. Kino, N. Kumagai, S. Makino, T. Mart,
T. Matsuda, T. Matsumura, N. Matsuoka, T. Mibe, M. Miyabe, Y. Miyachi, M. Morita,
N. Muramatsu, T. Nakano, M. Niiyama, M. Nomachi, Y. Ohashi, H. Ohkuma, T. Ooba,
D.S. Oshuev, C. Rangacharyulu, A. Sakaguchi, T. Sasaki, P.M. Shagin, Y. Shiino,
A. Shimizu, H. Shimizu, Y. Sugaya, M. Sumihama, Y. Toi, H. Toyokawa, A. Wakai,
C.W. Wang, S.C. Wang, K. Yonehara, T. Yorita, M. Yoshimura, M. Yosoi, and R.G.T. Zegers
Phys. Rev. Lett. 97 (2006) 082003 (1-5).
ơp → K + đ andġơp → K +Ę0 Reactions at Forward Angles with Photon Energies from 1.5 to 2.4 GeV.
Theġ
M. Sumihama, J.K. Ahn, H. Akimune, Y. Asano, C. Bennhold, W.C. Chang, T. Corthals,
S. Date, H. Ejiri, H. Fujimura, M. Fujiwara, M. Guidal, K. Hicks, T. Hotta, K. Imai,
T. Ishikawa, T. Iwata, H. Kawai, Z.Y. Kim, K. Kino, H. Kohri, N. Kumagai, S. Makino,
T. Mart, T. Matsumura, N. Matsuoka, T. Mibe, M. Miyabe, Y. Miyachi, M. Morita,
N. Muramatsu, T. Nakano, M. Niiyama, M. Nomachi, Y. Ohashi, T. Ooba, H. Ohkuma,
D.S. Oshuev, C. Rangacharyulu, A. Sakaguchi, T. Sasaki, P.M. Shagin, Y. Shiino,
H. Shimizu, Y. Sugaya, H. Toyokawa, A. Wakai, C.W. Wang, S.C. Wang, K. Yonehara,
T. Yorita, M. Yosoi, and R.G.T. Zegers
Phys. Rev. C 73 (2006) 035214 (1-12).
Measurements of the Generalized Electric and Magnetic Polarizabilities of the Proton at Low Q2 Using
the Virtual-Compton-Scattering Reaction.
P. Bourgeois, Y. Sato, J. Shaw, R. Alarcon, A. M. Bernstein, W. Bertozzi, T. Botto,
J. Calarco, F. Casagrande, M. O. Distler, K. Dow, M. Farkondeh, S. Georgakopoulos,
S. Gilad, R. Hicks, M. Holtrop, A. Hotta, X. Jiang, A. Karabarbounis, J. Kirkpatrick,
S. Kowalski, R. Milner, R. Miskimen, I. Nakagawa, C. N. Papanicolas, A. J. Sarty, S. Sirca,
E. Six, N. F. Sparveris, S. Stave, E. Stiliaris, T. Tamae, G. Tsentalovich, C. Tschalaer,
W. Turchinetz, Z.-L. Zhou, and T. Zwart
Phys. Rev. Lett. 97 (2006) 212001 (1-4).
Measurement of Evaporation Residue Cross-Section of the Reaction 30Si + 238U at Subbarrier Energies.
K. Nishio, S. Hofmann, F.P. Hessberger, D. Achermann, S. Antalic, V.F. Comas, Z. Gan,
S. Heinz, J.A. Heredia, H. Ikezoe, J. Khuyagbaatar, B. Kindler, I. Kojouharov,
P. Kuusiniemi, B. Lommel, R. Mann, M. Mazzocco, S. Mitsuoka, T. Ohtsuki, A.G. Popeko,
S. Saro, H.J. Schott, B. Sulignano, A. Svirikhin, K. Tsuruta, and A.V. Yeremin
Europian Physical Journal A 29 (2006) 281-287.
Status of the Electron Accelerator for Radioanalytical Studies at Tohoku University.

ĵĸ
T. Ohtsuki, H. Yuki, K. Hirose, and T. MitsugashiraCzech Journal of Physics 56 (2006) D391-398.
Radiochemical Studies at the Cyclotron Laboratory Tohoku University.
T.Ohtsuki, K. Shikano, H. Yuki, K. Hirose, and K. Takamiya
Czech Journal of Physics 56 (2006) D425-432.
Conceptual Design of an Isochronous Ring to Generate Coherent Terahertz Synchrotron Radiation.
H. Hama, H. Tanaka, N. Kumagai, M. Kawai, F. Hinode, T. Muto, K. Nanbu, T. Tanaka,
K. Kasamsook, K. Akiyama, and M. Yasuda
New J. Phys. 8 (2006) 292.
Papers Published in International Conference Proceedings
Low-Energy Li+D Reactions with Li Target in Various Phases.
H. Yonemura, J. Kasagi, M. Honmo, Y. Ishikawa, T. Wang and Y. Zhang
Proceeings of International Conference on Reaction Mechanism and Nuclear Structure at
the Coulomb Barrier, AIP Conference Proceedings 853 (2006) 372-377.
Super Coherent THz Light Source Based on an Isochronous Ring with Very Short Electron Bunches.
H. Hama, K. Akiyama, F. Hinode, K. Kasamsook, M. Kawai, T. Muto, K. Nanbu, T. Tanaka,
M. Yasuda, and H. Tanaka
Proceedings of the 28th International Free Electron Laser Conference, FEL2006, Berlin,
Germany (2006) 371-374.
A Compact Low Emittance DC Gun Employing Single Crystal Cathode of LaB6.
K. Kasamsook, K. Akiyama, H. Hama, F. Hinode, M. Kawai, T. Muto, K. Nanbu, T. Tanaka,
and M. Yasuda
Proceedings of the 28th International Free Electron Laser Conference,
FEL2006, Berlin, Germany (2006) 680-683.

Ԉȅ"QQSPWFE&YQFSJNFOUTĵĺ໹଼ 18 ාഽஜ‫ܢ‬न఼‫ه‬ఴ֚။ນ‫ه‬ఴ๔࣢

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କளညܳߗࢢͥ͢ͅ‫ڐ‬८͈௯ૺ

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໹଼ 18 ාഽࢃ‫ܢ‬न఼‫ه‬ఴ֚။ນ‫ه‬ȁȁȁȁȁఴȁȁȁȁȁྴ

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