26Al and 36Cl AMS system at the Univer sity of Tsukuba: A pr ogr ess r epor tKimikazu Sasa 1), Yasuo Nagashima 1), Tsutomu Takahashi1), Riki Seki1), Yuki Tosaki1), Keisuke Sueki1),
Kotar o Bessho2), Hir oshi Matsumur a 2) Taichi Miur a 2) and Ming He3)
1) AMS Gr oup, Tandem Acceler ator Complex, Univer sity of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibar aki, 305-8577, J apan
2) Radiation Science Center , High Ener gy Acceler ator Resear ch Or ganization, 1-1 Oho, Tsukuba, Ibar aki, 305-0801, J apan3) Depar tment of Nuclear Physics, China Institute of Atomic Ener gy, 102413, Beijing, 275(49), China

15 kV

35Cl-FC

120magnet

EQ

AMS ion sour ce

AMS-IS

EinzelESAutomaticsample
changer

Inflection
FC ES

magnet

BPM

FC

36Cl-

37Cl-FC

115kV
EQ

36Cl-

12UD Pelletron
tandem accelerator

ES

12Cl 39th floor
Ion sour ce r oom

EQ ES

FC
QM

ES
EQ

Objectslit

ST(25 samples on the r otating wheel)

New Ter minal

Acceleratorr oom

5th floor

QM

Imageslit

SW
BPM

12Cl3+ST

Instead of the GVM stabilizer, a slit cur r ent feedback
contr ol system is used as a ter minal voltage stabilizer . A
molecular pilot beam method is applied to stabilize theter minal voltage. The ter minal voltage is kept stably
within 0.1% accur acy by this method. A tr i-car bonmolecular , 12C 3− ion is used as the pilot beam for 36ClAMS. It is impor tant to r educe the str ong 36S isobar ic
inter fer ence on 36Cl measur ements.

QM

SF6 SF6STST

1st tar get room
QMSWQM

ObjectslitAnalyzer
magnet

2nd targer roomImageslit

E- E
2nd stripper 8 -electrostatic TOF
foilchamber detector
deflector
chamber
ST45 -magnet
QM SW
QMSTST

AMS-beam line
46.5 m26Al-AMS

AMS
ion source

36Cl-AMS measur ement: 36Cl14+/35Cl- [counts/

26AlO -Inflection mag.

26Al13+FC

36

26Mg11+
26Mg12+

Vt =10.2MV

1st Str ipper
foil

45°mag.
deflector（8°）
2nd stripper
foil(40 g/cm 2)

26Mg7+

Slit
cur r ent
feedback

26Mgn+

1054 counts

Standar d sample
26Al/27Al=7.44 10-11
5 minutes measur ement

12)
26Alm’+ (n’ 13)
26Mg7+
26Al7+

Analyzingmag.

(77.7 MeV)

Outline of 26Al-AMS
Full str ipping technique:C]
Pilot beam: 26MgO Beam cur r ent of AlO fr om Al2O 3 sample : 1.5 A
26Al13+/27AlO - [counts/

Standar d sample
26Al/27Al=4.69 10-12
10 minutes measur ement

8 electr ostaticdeflector

2nd str ipper
foil

AMS data analysis

16 counts

No count

Standar d sample
26Al/27Al=4.99 10-13
10 minutes measur ement

Blank sample
80 minutes measur ement(100MeV)
SSD 300 m
45 45mm 2

Double gas E sections (2004 - )ΔE 1 gate
ΔE 2 gate

36Cl

ΔE 1 gate

Non gate

New tar get cor n0

Supernatant

2mm

Precipitate (AgCl)
3 M NH4OH (2 mL)sat. Ba(NO3)2 (3 mL)

Sulfur Reduction (2 times)

Filtration (Filter Paper)
Filtrate ([Ag(NH3)2] Cl )Precipitate (BaSO4)

A benzene satur ated
solution of Fuller ene (C 60)
for 12C 3- pilot beam.
[7.6 l / AgCl: 1 mg]

13 M HNO3 (0.5 mL)

0.32330 counts

0.260

708090Supernatant

E- E100

Run No.

The standar d deviation of the fluctuation of the 36Cl/35Cl r atio
is kept within 3%

Standar d sample: 36Cl / 35Cl=5.9

10-11

Upper limit of the 26Al-AMS sensitivity: 5.8×10-15

Diameter of a sample pocket: 1mmSample: AgCl 1 5mg
Ta sheet
In or der to r educe 36S influence.

Precipitate (AgCl)
Washing (with 0.01 M HNO3, 2 times)
Washing (with 99.5% C2H5OH)
Drying (130 C, 3 h)Char ge fr action F(q) of 35Cl9+ incr eased 1.5 times
fr om 20% to 30% .

UTTAC

Corresponding author:
Kimikazu SASA

J apanksasa@tac.tsukuba.ac.jp
Tsukuba science city Univer sity of Tsukuba

Equilibr ium char ge fr action of 35Cl ion after passage thr ough a
car bon foil. [by Shima et al., ]Summar y of 26Al-AMS

Aｌ cor n

3 minutes measur ement

After the AMS-9 confer ence, 36Cl-AMS is able to be
per for med with 10 MV ter minal voltage instead of 9 MV.
10MV

AgCl sample
Ta sheet

Cr oss sectional view of the target cor nCentrifugation (2000 rpm, 15 min)

9MV

A gasΔE - SSD E counter telescopeCentrifugation (2500 rpm, 10 min)7777counts

50Ar amid film
4 m

Sample: 1 5 g
A few mg of AgCl sample

30% H2O2 (1 mL)
13 M HNO3 (1 mL)
0.3 M AgNO3 (1 mL)

E0.4

40

36Cl14+Sample preparation

36S

0.5

26Al is ver y clear ly separ ated from 26Mg with the detector .

26Al-AMS has also pr ogr essed in AMS technique. The ions extr acted fr om the ion sour ce were changed
to 26AlO − ions fr om 26Al− because sever al advantages would be expected. 26MgO − molecular ion is used as
the pilot beam. After passing thr ough the acceler ator at 10.2 MV, 26Al7+ and 26Mg7+ with the ener gy of
77.7 MeV are selected by the analyzing magnet. 26Al7+ ions ar e changed to full str ipped 26Al13+ ions by asecond char ge exchange foil and then they ar e separ ated by the following ener gy and momentum
selector s. The effective detection limit is reached to better than 5.8 10−15 for 26Al/27Al r atio.

ΔE 1

A new EE detector

0.6

30

have been measur ed. Results show that theisotope effect of char ge distr ibutions between
35Cl and 37 Cl ions has not been obser ved when
they ar e compar ed at equal exit ener gy.

A new E-E detector

Y-planeEQ3-4No. 18

2037Cl ions after the passage thr ough a car bon foil

-120.7

10Equilibr ium char ge

60

In or der to reduce 36S influence

No. 20026Al

50

Cl9+C 108 g/cm2
95.026 MeV
92.974 MeV
2.5128 MeV/u
19.0 MeV/(mg/cm2)
0.01079
0.06752
0.21430.35140.29320.05877
0.003979
14.041
1.0695
distr ibutions of 35Cl and45 magnet

0.126Al

40375mm

We impr oved the acceler ator
tr ansmission fr om 30% to 60% .

E- E
detectorchamber

No. 1899 counts

E- E

26Alm+

26Mg n’+ (m’Switchingmag.

35

30

C-foil [ g/cm 2]

Iso-butane 670 Pa
EQ1-2

Standar d sample ( Cl/ Cl =6.5×10 )35

26Al13+

27AlO -Cl / Cl (counts/μC)

ΔE-E detector

26Al

36120°mag.

C]

Pilot beam: 12C 3Beam cur r ent of Cl- from AgCl sample: 20 A

20Cl9+C 108 g/cm290 MeV
87.948 MeV
2.5128 MeV/u
19.0 MeV/(mg/cm2)
0.010800.06704
0.21630.34940.2941
0.05876
0.003655
14.04
1.069

X-planeSample (10–20 mL)

E

10ΔE 2

Beam envelope

15mm36Cl-AMS

26MgO -0(x, x’)=(y, y’)=(1.5mm, 10mr ad)

AMS beam line

45 -magnet

0.00011036Cl- beam tr anspor t

Str ipper foils at the ter minal
36Cl- ⇒ 36Cl9+(A/q=4)
12C - ⇒ 12C 3+(A/q=4)3ST

8 -electrostatic
deflector

dE/dx
F(11+)
F(12+)
F(13+)
F(14+)
F(15+)
F(16+)
F(17+)
Mean charge qb
Distribution width

0.01

35I-Mag
Terminal
Object point pointemittanceemittance

36Cl14+ (100 MeV)FC0.1

Foil thickness attaining char ge equilibr ium: The optimum thickness of 2nd str ipper foil:
About 12-15 g/cm 2 [F(14+)]over 100 g/cm 212mm

QM

41.6 m

4th floor

16mm
8mm

2nd stripper
foil

Incidence
foil
Incident energy
Exit energy

8910111213141516170.001

10Incident ener gy of 35Cl [MeV/u]

4mm

36Cl9+ (100MeV)
ES : E lectr ostatic steer er
EQ : Electrostatic quadr upole(tr iplet)
QM: Quadr upole magnet(doublet)
ST : M agnetic steer er
SW : Switching magnetStr ipper foilof 35Cl and 37Cl ions passing thr ough a car bon foil

Charge fraction F(q) of 90MeV 35 Cl9+
emerging from a ca rbon foil

1by C.J .Sofield et al., 1984
This work

Cl + C35Cl [100MeV]

AMS-beam line

BPM FC STAnalyzer
magnet35

100

Automatic sample changer

7th floor
Stripperfoil

1000

EQ

BPM:Beam pr ofile monitor
ES : Electr ostatic steer er
EQ : Electrostatic quadr upole(tr iplet)
FC : Farad ay cu p
QM : Quadrupole magn et(doublet)
ST : Magnetic steer er
SW : Switch ing magnetAMS-IS

ES120 magnet

35Cl- -FC

VT=10 MV
Inflection
Ion Source 120 -magnet magnet(25samples)
35Cl-FCSlit

115 kV

12Cl 3Stripperfoil

12UD Pelletr on
tand em accelerator

University of Tsukuba, Tsukuba, Japan.
・MODEL : Vertical Tandem Van de Graaff
・Terminal voltage range: 2.0 - 11.0 MV
・Insulation Gas :SF6 pressure:
0.6 MPa
・Accelerator Tank :Height:17.9 mDiameter:
4.8 m
Volume :350 m3
Total weight: 120 ton
・Analyzing Magnet : ME/Z2=200 amu MeV

Sputter ing
ion sour ce

36Cl-Accelerator facility
NEC 12UD Pelletron tandem accelerator (1975)

2nd str ipper foil
We measur ed the char ge state distr ibution of 35Cl and 37Cl ions after the passage thr ough a car bon
foil in or der to optimize the thickness of 2nd str ipper foil.
Isotope dependence of equilibr ium char ge states

Char ge fr action

The pr esent status of the Tsukuba AMS system on the 12UD Pelletr on tandem acceler ator isr epor ted. At pr esent, long lived r adioisotopes of 26Al, 36Cl and 129I are able to be measur ed by theTsukuba AMS system. After the AMS-9 confer ence, sever al effor ts have been paid on the 26Al and36Cl-AMS system in or der to impr ove the per for mance. Sever al impr ovements have been appliedon the AMS beam line, so that 36Cl-AMS is able to be per for med with 10 MV ter minal voltage
instead of 9 MV. Ther efore, the ener gy of the 36Cl9+ beam incr eases fr om 90 MeV to 100 MeV.
This ener gy incr ement helps us to get mor e clear separ ation between 36Cl and 36S.

Tsukuba AMS system (36Cl-AMS)

Ion Source(25 samples)

Char ge equilibr ium thickness
T eq [ g/cm 2]

Introduction

E [MeV]

Summar y of 36Cl-AMS
As a result of these impr ovements, the detection efficiency of 36Cl incr eased to 1.5 times and thediscr imination between 36Cl and 36S was much impr oved. Over all accur acy is ±3% and the effective
detection limit is r eached to 2 10−14 for 36Cl/35Cl r atio.

Tandem Acceler ator Complex,
Research facility Center for Science andTechnology,
Univer sity of Tsukuba,
Tsukuba, Ibar aki, 305-8577,
J apanTel: +81-29-853-2494
Fax:+81-29-853-2565

Tandem Acceler ator Complex

Acknowledgement
This wor k is suppor ted in par t by the Grand-in-Aid for Scientific Resear ch of the Ministr y of Education, Science,
Spor ts and Cultur e of J apan.