But have never been used to study the structure of short-lived radioactive nuclei.

a large accelerator complexincluding a cooler ring and a collider

M. Wakasugi, et al., Nucl. Instr. and Meth. A 532 (2004) 216-233

Total length 650mmTrapping region 〜 260mm

42 thin electrodes are stacked every 11 mm.

Be(t=1mm) window

110 mm

35 mm

Inside the SCRIT

dd

el

dd

M

fr

F0C(q)

2

fr

1

12k

1

Msin2

2

k

2

k1

M： Mass of nucleus

F0C(q)

F

0C(q) = 4 (r)

sinqr

qrr2

0

dr

(r) =

1

2 2rF

0C(q)sin(qr)q

0

dr

| Fc(

q)

|2

|Fc(

q)|2

Momentum transfer (MeV/c)

20 30 40 50 60 70 801E-16

1E-14

1E-12

1E-10

1E-8

1E-6

1E-4

0.01

1

elas

tic

cros

s se

ctio

n (b

arn)

scattering angle (degree)

100 MeV 300 MeV 500 MeV 800 MeV

Energy of e- beam

I. Externally injected ions trapped ?

II. Luminosity can be reached to 1027 s-1cm-2 ?

Those three calorimeters for the energy of scattering electrons

Residual gases

Scattered electron

PRL 100, 164801 (2008)

PRL 102, 102501 (2009)

Non-uniform distribution

40 44 48 52 56 60 64 68 72 760

2

4

6

8

10

12lu

min

osit

y (1

025cm

-2s-1

)

beamcurrent (mA)

Higher luminosity can be expected with higher beam current.

ions(a)

(c)

(b)

(d)

(e)

SCRIT Longitudinal potential

SCRIT Longitudinal potential

SCRIT Longitudinal potential

SCRIT Longitudinal potential

SCRIT Longitudinal potential

ions

ions trapped

ions

ions

Elastic electron scattering

e

e’

q

0+

0 4 82 6 10r (fm)

c (r

)(fm

-3)x

10

-2

4He

12C

16O

40Ca

48Ca

208Pb

elastic scatteringcross section is largest (up to medium momentum transfer region)charge density distribution (charge form factor)

beyond mean-square charge radius by IS,muonic X-ray

| Fc(

q)

|2

|Fc(

q)|2

Momentum transfer (MeV/c)

2 s2 s

Cs ions Cs ionsCs ions

Cycle #1 Cycle #2 Cycle #3 Cycle #4

Total Cycle number is 18 in 2 seconds measurement

110 ms