History

• 2016 The 50th anniversary of the foundation.
• Apr 2015 Collaborative research division “Condensed Matter Nuclear Reaction” established.
• Jul 2014 Research building renovated and the Mikamine Hall completed.
• Dec 2013 Operation resumed after recovery from the Great East Japan Earthquake.
• Apr 2011 Approved as a Joint Usage/Research Center for Electron Photon Science.
• Mar 2011 Operation suspended due to damages by the Great East Japan Earthquake.
• Mar 2010 “Accelerator-based Light Source Building” completed.
• Dec 2009 Reorganized as “Research Center for Electron Photon Science”.
• Sep 2009 Electromagnetic calorimeter “FOREST” completed in the Gamma-ray Irradiation Room.
• Feb 2008 “High-frequency Power Source Building” completed.
• Sep 2006 Magnetic electrometer “NKS2” completed in the Second Experimental Room.
• May 2006 Electron-Positron test beam line operation started.
• Jul 2002 GeV Gamma-ray Irradiation building completed and started Hadron experiments.
• 1998 Organized as adjunct facility of Graduate School of Science.
• 1997 1.2 GeV Stretcher Booster Ring completed.
• 1988 World’s first observed coherent emission.
• 1982 150 MeV Pulse Stretcher completed.
• 1971 Pulse neutron source developed.
• 1967 300 MeV Electron LINAC completed.
• 1966 Established as an on-campus shared-use facility in nuclear physics.

Member

Facilities

High intensity electron linac

 

 

 

 

 

 

 

BST ring

 

 

 

 

 

 

 

Injector for BST

 

 

 

 

 

 

 

Chemistry Lab. (#3 experimental Lab.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NKS2

 

 

 

 

 

 

 

FOREST

 

 

 

 

 

 

 

RTAGX

 

 

 

 

 

 

 

t-ACTS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Accelerators and Beam properties

In ELPH, the electron and photon beam lines are provided for nuclear physics experiments and a radioactive isotope production. (Present Configuration (2015))

High intensity electron linac

The 300 MeV electron linear accelerator had been constructed in 1967. In the Great East Japan Earthquake (March 11, 2011), serious damages was inflicted on this linac and a low energy part of the linac was reconstructed as a high intensity electron linac. The linac consists of 90 keV thermionic cathode gun, a buncher section and eight 1m-long s-band accelerating structures. Maximum energy of the linac is 70 MeV without beam loading. The linac is operated with 300 Hz repetition rate and a peak current in macropulse is approximately 100 mA with 3 micro-sec pulse duration. The average beam current is about 100 micro-Ampere. This high current electron beam is used for radio isotope production by photonuclear reactions.

Linac Energy	Modulator Repetition	Macropulse Peak Current	Macropulse Duration	Average Current
50 MeV	300 Hz	〜130 mA	3.0 µs	120 µA
30 MeV	300 Hz	〜100 mA	3.0 µs	90 µA

Injector linac for BST

Injector linac for the Booster synchrotron ring.

Compact electron linac had been constructed as the injector for the booster synchrotron in 2012. The injector consists of a thermionic rf-gun, an alpha magnet, two s-band 3m-long accelerating structures, and transport line to the booster synchrotron. The maximum energy of injector is 90 MeV with beam loading. This linac has two beam lines for beam diagnostics, one is straight line and the other is 90 degree beam line with dispersion section.

1.3 GeV Booster-STorage ring (BST)

Combined function magnet.  It looks like an ordinary quadrupole magnet but has a special pole-face shape to generate the sextupole component, and thus the chromaticity correction can be accomplished with these magnets by introducing the dispersion function to the magnet location.

BST ring. The ring circumference is 50 m, and eight dipole magnets (blue pieces) deflect the electrons so as to guide the electron beam, while the focusing magnets (orange and red magnets) are used to keep the electrons circulating inside the vacuum chamber.

BST is an electron synchrotron which accelerates the electrons injected from the injector linac up to 1.3 GeV in maximum. The required energy to accelerate and store the electron beam is supplied by a 500 MHz rf cavity. By inserting a very fine carbon wire to the beam orbit of circulating electrons after the acceleration, high energy gamma rays are generated via bremsstrahlung. Two beam lines are operational to utilize such gamma rays. In a typical operation pattern, beam acceleration is immediately started just after the injection and finished within ~2 sec., and then stored electrons with ring current of 10~30 mA are consumed to generate the gamma rays over a duration of about 10~40 sec. Currently available operation energy is 1.3, 1.0 and 0.8 GeV, and typical ring current is ~10～30 mA.

Injection Beam Energy	Injection Repetition	Ring Top Energy	Storage Beam Current
90 MeV	~0.05 Hz (typ.)	0.8~1.3 GeV	~30 mA

Tagged photon beamline

The BST ring has two beamlines providing tagged photons. The typical properties of the tagged photon beams are summarized in the table:

Beam line	Energy Range (Rint Energy: 1.3 GeV)	# of Bins	Intensity	Duty
BST-Tagger-I	0.8 ~ 1.26 GeV	160	TBC	~60% (NKS2)
BST-Tagger-II	0.9 ~ 1.25 GeV	116	TBC	~50% (FOREST)

Photon beamline I

The photons are designed to be tagged with energies of 62%~98% with respect to the circulating electron energy of the BST ring. The number of tagging channels are 160. The details of the photon beam properties are under investigation.

Please contact to Dr. M. Kaneta (mail: kaneta@lambda.phys.tohoku.ac.jp).

Photon beamline II

The photons are designed to be tagged with energies of 62%~96% with respect to the circulating electron energy of the BST ring. The duty facto is approximately 50% (stable photon beam can be obtained for 8.5 s out of a 17 s cycle). The number of tagging channels are 116. The details of the photon beam properties are under investigation. Information before The Great East Japan Earthquake (March 11, 2011) can be obtained in a reference "The second GeV tagged photon beamline at ELPH"

Reference: T. Ishikawa et al., Nucl. Instr. and Meth. A 622, 1 (2010).

Please contact to Dr. A. Tokiyasu (tokiyasu-at-lns.tohoku.ac.jp -at- should be replaced with @).

Positron/electron beamlines for testing detectors

The positrons and electrons, which are produced at a metal plate in front of the bending magnet RTAGX by the photon beam, are provided at three beamlines in the GeV-γ experimental hall. The positrons and electrons are momentum-analyzed with RTAGX, and the energy spread of them is approximately 0.5% . The beam profile and intensity depend on the beam energy, and the diameter of the beam is roughly 20 mm, the intensity is roughly a few kHz. The positrons (or electrons) at the -30 deg beamline can be focused with a triplet quadrupole magnets thanks to a KEK cooperation. The polarity of the magnets can be changed. The details of the photon beam properties after the earthquake are under investigation. Information before can be obtained in a reference "A detailed test of a BSO calorimeter with 100-800 MeV positrons",

Reference: T. Ishikawa et al., Nucl. Instr. and Meth. A 694, 348 (2012).

Beam	Beam line	Maximum beam energy
Positron / Electron	± 30 deg	~840 MeV
Positron	-23 deg	~1000 MeV

Please contact to Dr. A. Tokiyasu (tokiyasu-at-lns.tohoku.ac.jp -at- should be replaced with @).