The Nanosecond bunching system at KIGAM Tandem Accelerator Korea Institutes of Geoscience, and Mineral Resources G.D. Kim, W.Hong, J.K.Kim, H.W.Choi, and H.J.Woo Korea Atomic Energy Research Institutes J.W.Chang 2002. 8.29-30

Introduction The nuclear data production project as one of the nation-wide nuclear R&D programs has been in process of performance from 1999 at KIGAM, Its main goal is to develop a highly reliable nuclear data production system. KIGAM is interested in the neutron capture cross section of neutron energies from 1 MeV to 2 MeV, which is corresponded to a fusion reaction. So we have measured neutron capture cross sections of a few materials, such as 63Cu and 186W, by MeV continuous neutron beam from 3T(p,n)3He reaction and an activation method.

KIGAM’s Data

Pulsing and bunching principle f l e c t o r d o u b l e b u n c h i n g s y s t e m 4 M H z 8 M H z s l i t Beam Charge : negative y z x Dt = 4 E d Dy /{ (q Vo w)(l12 +2 l1 l2 )} When E is 28 keV, d is 3 cm , Δy is 0.2 cm, q is 1 coulomb, Vo is 81 V, w is 4 MHz, l1 is 8 cm, and l2 is 28.3 cm, Beam width of 64 ns can be obtained .

A program was made to show the bunching shape and the compression ratio of incident beam. Applied alternative voltage of each electrod, the electrod size, intervals of electrodes and slit size were determined by this program.

V deflector = 82 V, V buncher = 1450 V Bunching system simulation code and Results * FWHM V deflector = 82 V, V buncher = 1450 V

The beam dynamics for each component was calculated by an NEC - beam transport code to confirm an optimum beam shape. x size : 6.98 mm x angle : 1.88 mR y size : 6.24 mm y angle : 5.06 mR target

1.7 MV KIGAM Accelerator

Pulsing and bunching system

Electronics

Bending Magnet BR = 144 (MT/z2)0.5 kgauss-cm R=58.95 cm Simulation BR = 144 (MT/z2)0.5 kgauss-cm R=58.95 cm Maximum magnetic field : 1 T C type( Remote control by RS232 ) Weight : core 340 kgf, coils 70 kgf (472m) -14 turns x 12 layers / coil

New beam line

New neutron experimental room Beam direction

Summary The specification of neutron bunching beam is that the repetition rate of this system is 8 MHz, the width is about 2 ns, duty factor is about 20 % and proton energy dispersion is about 6 keV. Also beamline, each electronics, bending magnet and new neutron scattering experimental room are under fabrication.