1Preliminary Measurement of
10Be isotope by 1 MV AMS

Hong, Wan
Korea Institute of Geoscience and Mineral Resources (KIGAM)

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group2Ion beam application group of KIGAM
500 kV single ended Implanter

1 MV AMS

1.7 MV Pelletron

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group3

Applications of the group

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group4

Cosmogenic nuclide, 10Be

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group5

Cosmogenic nuclide, 10Be
 Half-life: 1.5 million year Produced by spallation reaction between cosmic rays and 16O or 14N
 1.21 ± 0.70 x 106 atoms/cm2/yr in atmosphere 0.35 ~ 1.89 x 106 atoms/cm2/yr in ice core and sediment The production rate is inversely correlated with geomagnetic dipolemoment.
 Abundance of 10Be in atmosphere 7 x 106 atoms/m3 in troposphere 1.3 x 106 atoms/m3 in stratosphere In-situ production in rocks by neutron spallation with 16O and by muon
induced reaction
 Used to study on geology, mineralogy and geography as a tracer
 Isotope ratio: 10Be/9Be = 1 x 10-11 in marine sediment= 5 x 10-14 in rocks (in-situ)
The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group6

Specifications of AMS of KIGAM
 Dimension : 4.2 m × 6.2 m
 50 sample multi-cathode sputtering source (35 kV, 5 µA for beryllium) Low energy bending magnet: 90 deg., 9.8 MeV · amu
 Bouncing system: 3kV, 100 Hz, 14C, 10Be, 26Al measurements areavailable 1 MV Tandem accelerator (2mA) with Ar stripper
 Analyzing magnet: 90 deg., 63 MeV · amu
 Absorber foil in front of ESA, 150 nm Si3N4 foil
 Electric spherical energy analyzer (ESA): 120 deg., 60 kV
 Ionization chamber with two anodes, 75 nm Si3N4 window Counting time: 40 minutes per a Be sample in typical case
 Background: 10Be/9Be = 2 × 10-14 in typical case
The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group7

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group81 MV AMS system of HVEE (4110Bo(4110Bo- AMSAMS- 3)
The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group

9Accelerator Mass Spectrometer at KIGAM
Injector magnet
9.8 amu·MeV,amu MeV, 100 Hz

Tandem Accelerator 1MV, 2mA

Analyzing magnet 63
amu·MeV
amu MeV

Stable isotopedetection station

Sputter type
Ion source 50targets

Rare isotope detectionstation, Gas counter
with 75nm SiN window

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

ESA , 60 kV

Ion Beam Application Group

10SO110 Negative Ion source At Cs temperature = 95 ˚CMax. Beam current =~ 100 µA for C~ 300 nA for Al~ 5 µA for BeO-90

1.8e-7
Time vs Temperature
Time vs Current

1.6e-7
1.4e-770

1.2e-7601.0e-750
8.0e-840

Current (A)Temperature (degreeC)80

6.0e-830

4.0e-820

2.0e-8100.00102030

40Time (min)The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group11

LE magnet scanning (BeO target)
1e-4
16

1e-5

O
9Beam Current (A)

1e-6

BeO

1e-7
1212C

18
13

C
12
CH

1e-8

C2O

1e-9
1e-10
1e-11
40

45

5055

60

65

7075

80

Magnet Current (A)The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group12Accelerator condition

14C measurement: 950 kV
26Al measurement: 700 kV
10Be measurement: 1000 kV (1.40 MeV)

46

C2+ Stripping yield (%)

 Terminal voltage

48

44
42
40
38
36
34
32
0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

-2

Stripper pressure (10 torr)

 Ar stripper condition (transmission yield)
14C measurement: 2.1 x 10-2 torr (~ 12C2+ / 12C1- = 47 %)26Al measurement : 1.7 x 10-2 torr (~ 27Al1+ / 27Al1- = 30 %)
10Be measurement : 1.2 x 10-2 torr (~ 9Be1+ / 9BeO1- = 47 %)The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group13

Stable Isotope Measurement

14C, 10Be, 26Al
13C, 9Be, 27Al
12C

Movable FC
Fixed FC

 Movable FC position Beam center: 76 mm

13C measurement: 150 mm
27Al measurement: 15 mm
9Be measurement: 209 mm

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group14

Absorber foil
 Masses of 10Be and its isobar, 10B1398.472 keV)
10Be: 10.0135 (1398.486 keV)

10B: 10.0129 (∆M: 0.0006 (60 ppm)
∆E before the foil: 0.014 keV (10 ppm)
 Si3N4 absorber
Thickness = 150 nm
dE at the foil of 10Be = 170.72 keV

dE at the foil of 10B = 221.04 keVTrans. Energy of 10Be = 1227.8 keVTrans. Energy of 10B = 1177.43 keV∆E after the foil: 50.34 keV (4.1 %) Beam disperses at the foil

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group15

Electrostatic spherical Analyzer

 Angle: 120 ˚ Gap between electrodes: 25 mm

 Radius: 650 mm

 Maximum bias: 60 kV

 14C measurement: 55 kV

 10Be measurement: 49 kV

 26Al measurement: 55 kV
The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group16

Gas Ionization Chamber
 Bias: 300 V
 Gas: Isobutane
 Window: Si3N4, 75 nm
 Window size: 10 mmΦ
 Length: ~430 mm
 Acquisition system: MPA,FASTCOM
 Gas pressure
14C measurement: 8.4 mbar
26Al measurement: 7.7 mbar
10Be measurement: 7.2 mbar

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group17A typical 10Be spectrum
400
350

250200150

10Be

Channel 2 (Eres)

300

10050

nt

10BCou

10
20
30
40
50

0100

200

300

400

0500

Channel 1 (dE)60

Detector gas pressure: 7.2 mbar
The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group18Correction curve of 10Be/9Be ratio Counting efficiencydecreases due tobeam dispersion at
the absorber foil
 Counting efficiency~6 %The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group19

Results of standard and blank samples
Sample ID

Certified
10Be/9Be

Raw 10Be/9Be

Corrected
10Be/9Be

Error

Error (%)

blank-5.90 × 10-16

1.63 × 10-14

7.59 × 10-15

46.63

5-1

2.71 × 10-11

1.56 × 10-12

2.71 × 10-11

1.44 × 10-13

0.53

5-2

8.56 × 10-12

4.95 × 10-13

8.53 × 10-12

7.95 × 10-14

0.935-3

6.32 × 10-12

3.69 × 10-13

6.35 × 10-12

6.22 × 10-14

0.98

5-4

2.85 × 10-12

1.67 × 10-13

2.87 × 10-12

5.14 × 10-14

1.796-1

9.72 × 10-13

5.55 × 10-14

9.57 × 10-13

3.08 × 10-14

3.226-2

5.35 × 10-13

3.04 × 10-14

5.27 × 10-13

1.88 × 10-14

3.56

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group20

Reproducibility of 10Be measurement

Be-10/Be-9

Be-10 AMS Measurements
1.80E-1208.07.08-1

1.60E-1208.07.08-2
08.07.08-3

1.40E-12

12.23.08-1
12.23.08-2

1.20E-12

12.23.08-3

1.00E-12
8.01E-13
6.01E-13
4.01E-13
2.01E-13
1.00E-15
blk5-1

5-2

5-3

5-4

6-1

6-2Blanks & Standards

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group

21

Unknown sample measurement of 10Be
Sample nameRaw 10Be/9Be(blank value subtracted)

NR-1

10± σ

Be/9Be(counting efficiency corrected)± σ3.773E-15

9.499E-16

1.386E-13

2.867E-14NR-2

3.600E-15

8.087E-16

1.334E-13

2.441E-14NR-3

4.364E-15

1.766E-15

1.564E-13

5.332E-14

NR-4

4.577E-15

1.518E-15

1.629E-13

4.581E-14

NR-5

9.238E-16

5.078E-16

5.261E-14

1.533E-14

NR-6

1.616E-15

6.463E-16

7.350E-14

1.951E-14

NR-7

6.868E-16

1.103E-15

4.546E-14

3.331E-14

NR-8

1.589E-14

8.391E-15

5.044E-13

2.533E-13

DLR-2

1.802E-14

9.491E-16

5.686E-13

2.865E-14

DLR-3

1.972E-14

1.018E-15

6.200E-13

3.073E-14DLR-4

2.142E-14

8.939E-16

6.714E-13

2.698E-14

DLR-5

3.004E-14

1.501E-15

9.314E-13

4.530E-14

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group

22Summary
 A compact AMS system with 1 MV TV installed at KIGAM in 2007 (thesecond AMS machine in Korea) has dedicated to not only 14Cmeasurement but also 10Be measurement
 Be measurement with a AMS with small TV is a challenge Key point of successful 10Be measurement is effective suppression ofisobar, 10B.
 An absorber foil (Si3N4) with thickness of 150 nm was adopted toenhance the energy difference between Be and B isotopes.
 Large counting efficiency change due to using of a foil should be
estimated and corrected With this effort, almost all kind of samples except for in-situ rocksamples could be measured successfully.

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group23

The 7th International Workshop on Accelerator Operations (WAO-7), April 12 – 16, 2010, Daejeon, Korea

Ion Beam Application Group