Korea Institutes of Geoscience, and Mineral ResourcesG.D. Kim, W.Hong, J.K.Kim, H.W.Choi, and H.J.Woo

Korea Atomic Energy Research InstitutesJ.W.Chang

The Nanosecond bunching system at KIGAM Tandem Accelerator

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.

Neutron energy (MeV) 0 1 2 3 4

Neu

tron

cap

ture

cro

ss s

ectio

n [m

b]

0

4

8

12

16

20

63Cu(n,g)

P.White et. els

ENDF-6

OURS

V.A.TOLSTIKOV

Neutron energy [MeV]

1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0

Ne

utr

on

to

tal cro

ss s

ectio

n [

ba

rn]

5.5

6.0

6.5

7.0

7.5

8.0

ours

P.W.Miller

ENDF-6

KIGAM’s Data

Neutron energy [MeV]0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2

Ne

utr

on

to

tal c

ross

se

ctio

n [

ba

rn]

0

1

2

3

4

5

6

Cu(n,tot)

Ours

Miller (52)

JEF-2.2

Neutron energy [MeV]

0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8

Ne

utr

on

ca

ptu

re c

ross

se

ctio

n [

mb

]

15

20

25

30

35

40

45

50

55

M.Lindner (J.NSE.59,381,197604)

P. White (J.NE. 19,325,1965)

ours

ENDF-6

Pulsing and bunching principle

double bunching system

slit

deflector

8 MHz4MHz

y

z

x

t = 4 E d y /{ (q Vo )(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,

is 4 MHz, l1 is 8 cm, and l2 is 28.3 cm, Beam width of 64 ns can be obtained

Beam

Charge : negative

.

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.

Relative position (cm)

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

Par

ticle

s / 0

.01

cm

0

50

100

150

200

250

at the targetafter the targetbefore the target

Bunching system simulation code and ResultsBunching system simulation code and Results

No. Z (cm) beam width (ns) *1 314.71 5.612 286.15 1.433 257.29 5.714 228.08 18.055 199.45 27.756 170.41 36.417 141.55 51.398 112.76 73.68

* 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- plane

y- plane

Acc. MQT

SWMag.

slit

BendMag.

x size : 6.98 mmx angle : 1.88 mRy size : 6.24 mmy angle : 5.06 mR

x size : 6.98 mmx angle : 1.88 mRy size : 6.24 mmy angle : 5.06 mR

target

1.7 MV KIGAM Accelerator

2 2

1 4 2

2 0R 3

S U S

12

.5

22

.5

9 .7 1 0 .3

1 0

3

1

54

64

1

2 2 .4

1

3

1

º§ ·ê ·Î¿ ìÁ î(5 0 m m )

1 3

R 5 .2 5

5 9 .0

º§ ·ê ·Î¿ ìÁ î

11 .1

33

1

R 5 .2 5

9 3 .6

7 8 .2

8 4 .2

R 5 .5

2 5 9 .6

2 7 8 .3

270 cm

150 cm

RF Source

vaccuum gauge

einzellense

Roughpump

106.

5 cm

SF gas entrance

TMP

SNICS source

Steerierfeedthru

TMP

faraday cup

slitBPM

buncher

ionsource magnet

MQD

ERDchamber

wall

45slit

30

BPM

500 cm

650

cm

detetctor Neutronchamber

collimator

GateValue

o

Implantationchamber

o Faradaycup

Slit

Neutronchamber

Faradaycup

AnalyzingMagnet

R =58.95 cm

BPM

Steerier

Acceleration Tank

bendingmagnet

Steerierfeedthru

Scanner

SF gas exit

Pulsing and bunching system

KIGAM BUNCHER SYSTEM

283 mm

Einzellense

Deflector

Slit

Slit

Slit mover

Buncher chamber

Buncher

Gatevalve

Dummy

Electronics

Delay

50 W

4 MHz

8 MHzPulsegenerator

input

AC

-5V ~ +5 V

Amplifier

Buncher

output

AC

0 V ~ 5 kV

input

AC

-5V ~ +5 V

300 W

Amplifier

Deflector

output

AC

-0.5 k V ~ +0.5 kV

LCRresonance

LCRresonance

Bending Magnet

C type( Remote control by RS232 )

Weight : core 340 kgf, coils 70 kgf (472m)

-14 turns x 12 layers / coil

Simulation

BR = 144 (MT/z2)0.5 kgauss-cm

R=58.95 cm

Maximum magnetic field : 1 T

New beam line

352 1882

FC BPM

Gauge

vaccum exit

Steering magnetXYInsulator

836

1581152

70

700 1180

150

TMP

Rotary pump

TOF chamber

Gate valve

New neutron experimental room

Beam direction

Summary

The specification of neutron bunching beam is that the repeti tion 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.