Progress of an accelerator mass spectrometry system on the Tsukuba 12UD Pelletron tandem accelerator

Transcription

1 Progress of an accelerator mass spectrometry system on the Tsukuba 12UD Pelletron tandem accelerator -11th International Conference on Heavy Ion Accelerator Technology - Venezia (Italy) 8-12, June, 2009 Kimikazu SASA Tandem Accelerator Complex (UTTAC), University of Tsukuba, Japan Collaborators T. Takahashi, Y. Nagashima, Y. Tosaki, K. Sueki, Y. Yamato, N. Kinoshita, T. Amano, UTTAC, University of Tsukuba H. Matsumura, K. Bessho, RSC, KEK Y. Matsushi, MALT, The University of Tokyo

2 Outline of presentation Introduction - 12UD Pelletron tandem at the University of Tsukuba - AMS and facilities AMS system on the 12UD Pelletron tandem - Description of the Tsukuba AMS system - Recent progress - Performance of 26 Al, Cl and 129 I AMS Summary and future plans

3 Introduction - 12UD Pelletron tandem at the University of Tsukuba - AMS and facilities

4 UTTAC University of Tsukuba, Tandem Accelerator Complex Japan University of Tsukuba, Tsukuba science city 60 km from Tokyo in the northeast 2 accelerator facilities Proton Medical Research Center: PMRC Tandem Accelerator Complex: UTTAC 250 MeV Proton Synchrotron (2001) 12UD Pelletron Tandem Accelerator (1975) Proton Beam Radiotherapy 1MV Tandetron Accelerator (1987)

5 46.5 m 12UD Pelletron tandem accelerator (1975) Education Radiation University of Tsukuba, Tsukuba, Japan. Developments 2.5 % safety MODEL 2.5 %: Vertical Tandem 1.6 % Van de Graaff Hydrogen Terminal voltage range: 1-12 MV analysis Insulation 8.1 % Gas : SF 6 pressure: 0.6 MPa Accelerator Tank : Height: 17.9 m Atomic Diameter: AMS 4.8 m Physics Volume: 350 m % 41.5 % Total weight: 120 ton Analyzing Magnet : ME/Z 2 =200 amu MeV Material science In the early 15.4 % stage Nuclear physics 3000 hours/yr Nuclear Physics 17.8 % Now AMS IBA Material science : Electrostatic steerer : Electrostatic quadrupole (triplet) : Quadrupole (doublet) : Magnetic steerer SW : Switching 1st target room AMS: 42 % SF6 SW SF6 AMS-IS Inflection Ion Source (25samples) 35 Cl-FC Stripper Object Analyzer Image 12UD Pelletron tandem accelerator 9th floor Ion source room 7th floor 5th floor 4th floor 2nd targer room 2nd stripper SW Accelerator room 8 -electrostatic deflector TOF 45 - AMS-beam line E-ΔE detector 41.6 m

6 Upgrade of the 12UD Pelletron tandem 1UD: 3 accelerating tubes 1MV 12UD at Tsukuba University, Divided Compressed resistor geometry system type tube (6 units) We replaced with electron the old trap corona electrodes needles of V-shaped with (45 ) the aperture. divided resister system. Max MV Variable terminal voltage (No shorting column) V t = 1 12 MV

7 Beam energy for the 12UD Pelletron Terminal voltage: 1-12 MV Ion Au Ta I Ag Mo Br Cu Ti Ca Cl Si Al F O C B He H,D He H,D O C B Au Ta I Ag Mo Br Cu Ti Ca Cl Si Al F Beam energy (MeV)

8 Accelerator Mass Spectrometry Targets of AMS 10 Be (T 1/2 = yr) 14 C (5730 yr) 26 Al ( yr) Cl ( yr) 129 I ( yr) Accelerator High energy part Isobar, Isobaric Molecular suppression Magnetic analyzer Mass analysis Momentum analysis energy analysis Electrostatic analyzer Detectors 1 MeV/amu

9 AMS facilities 14 C-AMS 3MV Oxford, Groningen, Kiel, Arizona, NOSAMS, Nagoya, SNU, Multi Nuclides AMS LLNL, KIGAM 1MV 500 kv ETH, Georgia, UC-Irvine, Posnan, Peking, Paleo-labo, 10 Be, 14 C, 26 Al, Cl, 129 I, 5MV and higher ( originally for nuclear physics) LLNL(10MV), PRIME-Lab(8MV), ANO(9MV), ANU(14MV), ETH(6MV), Tokyo(5MV), Tsukuba(12MV), SWERC(5MV) 3MV VERA, LUND, JAEA-Mutsu,

10 AMS on the 12UD Pelletron tandem - Description of the Tsukuba AMS system - Recent progress - Performance of 26 Al, Cl and 129 I AMS

11 Tsukuba AMS system Progress of the Tsukuba AMS system Trial AMS measurement for 14 C Development of AMS system 14 C-AMS AMS ion source (original) Mass separator beam line Development of 26 Al, Cl-AMS Pilot beam methods (Instead of GVM control) Development of 129 I-AMS Cl AMS 9 MV 10 MV (Improved beam line) Background: Cl/Cl < Repetition accuracy:± 3 % Upgrade of the 12UD Pelletron (Resister system) GVM terminal control system

12 Tsukuba AMS system kv EL V T = Sputtering Ion Source [Original] (25 samples) FC FC AMS-IS 100 kv 1st Stripper Terminal voltage Vt 11 MV FC Object Inflection ME/q 2 =30 12UD Pelletron tandem accelerator Slit current feedback controller GVM A pilot beam method is used to stabilize the terminal voltage. EL : Einzel lens : Electrostatic steerer : Electrostatic quadrupole (triplet) FC : Faraday cup GVM : Generating volt meter : Quadrupole (doublet) : Magnetic steerer SW : Switching TPS : Terminal potential stabilizer The terminal voltage is kept stable within 0.1 %. 26 Al, Cl, 129 I - AMS 12 MV max. Pilot beams (isobar) TPS 26 AlO - 26 MgO - Cl - 12 C I- 97 MoO 2 - Analyzer ME/q 2 =200 Image SW 2nd stripper AMS-beam line 500 samples/year. 8 -electrostatic deflector 45 - TOF E-ΔE detector

13 Cl-AMS by the Tsukuba AMS system kv EL Sputtering Ion Source [Original] (25 samples) AMS-IS 35 Cl - FC FC 100 kv 37 Cl - 1st Stripper Terminal voltage Vt 11 MV V T = 10 MV FC Object Inflection ME/q 2 =30 12UD Pelletron tandem accelerator Slit current feedback controller GVM TPS Cl-AMS Cl - 12 C 3 - EL : Einzel lens : Electrostatic steerer : Electrostatic quadrupole (triplet) FC : Faraday cup GVM : Generating volt meter : Quadrupole (doublet) : Magnetic steerer SW : Switching TPS : Terminal potential stabilizer Target material AgCl + C 60 Cl ~ 20 μa V T Pilot beam 10 MV 12 C 3 Detection ion Cl 14+ Particle energy Detection range Back-ground 100 MeV Cl/Cl = ~ Cl/Cl < Repetition accuracy ± 3 % ( Cl/Cl ~ ) Analyzer ME/q 2 =200 Image Cl 9+ :100 MeV 12 C 3+ : 33.3 MeV SW 2nd stripper 8 -electrostatic deflector AMS-beam line Cl TOF E-ΔE detector

14 AMS Cs sputtering ion source kv EL Sputtering Ion Source [Original] (25 samples) FC FC AMS-IS 100 kv 1st Stripper Terminal voltage Vt 11 MV FC Inflection ME/q 2 =30 12UD Pelletron tandem accelerator Slit current feedback controller GVM Object TPS EL : Einzel lens : Electrostatic steerer : Electrostatic quadrupole (triplet) FC : Faraday cup GVM : Generating volt meter : Quadrupole (doublet) : Magnetic steerer SW : Switching TPS : Terminal potential stabilizer Original 25-sample changer Analyzer ME/q 2 =200 Image SW 2nd stripper AMS-beam line 8 -electrostatic deflector 45 - TOF E-ΔE detector

15 AMS Cs sputtering ion source kv EL Sputtering Ion Source [Original] (25 samples) FC FC AMS-IS 100 kv FC Inflection ME/q 2 =30 Automatic sample changer Sputtering ion source Slit & 120 1st Stripper Terminal voltage Vt 11 MV 12UD Pelletron tandem accelerator Slit current feedback controller GVM 100 kv Offset FC Object TPS EL : Einzel lens : Electrostatic steerer : Electrostatic quadrupole (triplet) FC : Faraday cup GVM : Generating volt meter : Quadrupole (doublet) : Magnetic steerer SW : Switching TPS : Terminal potential stabilizer Analyzer ME/q 2 =200 Image SW 2nd stripper AMS-beam line 8 -electrostatic deflector 45 - TOF E-ΔE detector

16 AMS Cs sputtering ion source kv EL Sputtering Ion Source [Original] (25 samples) FC FC AMS-IS 100 kv 1st Stripper Terminal voltage Vt 11 MV FC Object Inflection ME/q 2 =30 12UD Pelletron tandem accelerator Slit current feedback controller GVM TPS Cl - 12 C 3 - EL : Einzel lens : Electrostatic steerer : Electrostatic quadrupole (triplet) FC : Faraday cup GVM : Generating volt meter : Quadrupole (doublet) : Magnetic steerer SW : Switching TPS : Terminal potential stabilizer 35 Cl - 37 Cl - Analyzer ME/q 2 =200 Image SW 2nd stripper AMS-beam line 8 -electrostatic deflector 45 - TOF E-ΔE detector

17 AMS Cs sputtering ion source kv EL Sputtering Ion Source [Original] (25 samples) FC FC AMS-IS 100 kv 1st Stripper Terminal voltage Vt 11 MV FC Inflection ME/q 2 =30 12UD Pelletron tandem accelerator Slit current feedback controller GVM Object TPS EL : Einzel lens : Electrostatic steerer : Electrostatic quadrupole (triplet) FC : Faraday cup GVM : Generating volt meter : Quadrupole (doublet) : Magnetic steerer SW : Switching TPS : Terminal potential stabilizer Analyzer ME/q 2 =200 Image SW 2nd stripper AMS-beam line 8 -electrostatic deflector 45 - TOF E-ΔE detector

18 Upgrade of LEBT for 12UD Pelletron tandem accelerator Ion Source (25samples) 35 Cl-FC Inflection AMS-IS Einzel lens was replaced with electrostatic quadrupole (triplet). 13 Steerer Object point of the Inflection 676 Electrostatic quadrupole (triplet) 12UD Pelletron tandem accelerator Steerer Stripper : Electrostatic steerer : Electrostatic quadrupole (triplet) : Quadrupole (doublet) : Magnetic steerer SW : Switching Beam transport Injection energy Cl - : 103 kv H - : 120 kv Terminal voltage: 10 MV Electrostatic quadrupole (triplet) Object Analyzer Image 10 m 2nd stripper SW AMS-beam line TOF 8 -electrostatic deflector 45 - E-ΔE detector #1-1 tube

19 Tsukuba 12UD first unit (2009) Lower resistance at the entrance. Adjustment for the focusing effect Ion beam First unit Column 18 gap 0.37 G 1/2 gradient 4/6 gap short 3/6 gap short gap full live stringer stringer 0.37 G 0.55 G0.55 G 1.1 G 1.1 G 1.1 G 1/3 gradient

20 Terminal section (Charge exchange) Terminal section was modified to the large aperture canal (φ20) in Ion Source (25samples) 35 Cl-FC Inflection AMS-IS 12UD Pelletron tandem accelerator Stripper Negative Positive ions Carbon stripper : Electrostatic steerer : Electrostatic quadrupole (triplet) : Quadrupole (doublet) : Magnetic steerer SW : Switching 10 m 2 units Object Analyzer Image 2nd stripper SW AMS-beam line TOF 8 -electrostatic deflector 45 - E-ΔE detector

21 Terminal section (Charge exchange) Terminal section was modified to the large aperture canal (φ20) in Ion Source (25samples) 35 Cl-FC Inflection AMS-IS 12UD Pelletron tandem accelerator Stripper Negative Positive ions 2 units Object Analyzer Image : Electrostatic steerer : Electrostatic quadrupole (triplet) : Quadrupole (doublet) : Magnetic steerer SW : Switching Foil unit A (115 s) Carbon stripper Foil unit 10 Bm (115 s) Focal point 2nd stripper SW AMS-beam line TOF 8 -electrostatic deflector 45 - E-ΔE detector

22 Terminal section (Charge exchange) Terminal section was modified to the large aperture canal (φ20) in Ion Source (25samples) 35 Cl-FC Inflection AMS-IS φ4 12UD Pelletron tandem accelerator φ6 φ8 φ12 Carbon for AMS: 5 μg/cm 2 Stripper Object Analyzer Image Negative Positive ions Carbon stripper : Electrostatic steerer : Electrostatic quadrupole (triplet) : Quadrupole (doublet) : Magnetic steerer SW : Switching Foil unit A (115 s) Foil unit 10 Bm (115 s) Focal point 2nd stripper SW AMS-beam line TOF 8 -electrostatic deflector 45 - E-ΔE detector

23 Terminal section (Charge exchange) Terminal section was modified to the large aperture canal (φ20) in φ16 for AMS φ4 Ion Source (25samples) 35 Cl-FC Inflection AMS-IS 12UD Pelletron tandem accelerator φ6 φ8 φ12 Carbon for AMS: 5 μg/cm 2 Stripper Object Analyzer Image Negative Positive ions Carbon stripper : Electrostatic steerer : Electrostatic quadrupole (triplet) : Quadrupole (doublet) : Magnetic steerer SW : Switching Foil unit A (115 s) Foil unit 10 Bm (115 s) Focal point 2nd stripper SW AMS-beam line TOF 8 -electrostatic deflector 45 - E-ΔE detector

24 Beam transport of the 12UD Pelletron mm Object point Acceptrance 5 mm mrad Electrostatic Q-triplet LEBT Cl - Injection energy: 103 kv V T :10 MV 12UD accelerator tubes Terminal Carbon stripper Magnification: 1.5 times on the Terminal stripper. Beam spot on the stripper : φ 6 mm

25 Mass separator beam line 2 nd stripper Switching 8 electrostatic deflector 45 TOF Gas ΔE - E detector

26 Gas E-ΔE detector Iso-butane 670 Pa Cl S 100 MeV Cl in the gas detector.

27 Cl-AMS (2-dimensional spectrum) 500 (a) Cl 14+ (1003 counts) 500 (b) ΔE in channels Counts Cl standard Cl/Cl= sec 35 Cl current: 1929 μc (6.5 μa) E res in channels Cl S 14+ S ΔE in channels Counts Halite sample Cl/Cl < sec 35 Cl current:11492 μc (6.5 μa) E res in channels S 14+ Cl/Cl Background: E res in channels E res in channels Standard sample Blank sample Cl/Cl=

28 26 Al-AMS (2-dimensional spectrum) ΔE (channel) a) b) 26 Mg Mg Al 13+ (1054 counts) Standard sample 26 Al/ 27 Al = minute measurement E-ΔE (channel) ΔE (channel) Al 13+ Blank sample 80-minute measurement E-ΔE (channel) -Full stripping technique -Pilot beam: 26 MgO - - Beam current of AlO - from Al 2 O 3 sample : 1.5 μa - 26 Al is very clearly separated from 26 Mg. - Background of the 26 Al-AMS: <

29 Performance of the Tsukuba AMS system A pilot beam method is used to stabilize the terminal voltage. Target material V T Injection ion 26 Al-AMS Pilot beam Cl-AMS Detection ion Particle energy Al 2 O MgO 2 +Ag 10.2 MV 26 AlO - 26 MgO - 26 Al MeV < Target material V T Injection ion AgCl+C MV Pilot beam 129 I-AMS Detection ion Cl - 12 C 3 - Cl 14+ Particle energy Background Background 100 MeV < Target material V T Injection ion Pilot beam Detection ion Particle energy Background AgI+MoO 2 +Nb 9.7 MV 129 I - 97 MoO I MeV <

30 Applications by the Tsukuba AMS system Mainly for earth and environmental sciences. Nuclear safety research Atomic bomb, neutron fluence Soil sediment Rock meteorite Groundwater, rain, ice Biological sample Limestone Rain water Human hair Hiroshima A-bomb sample Soil Meteorite Ice core

31 Summary and future plans 12UD Pelletron tandem at the University of Tsukuba We have upgraded the 12UD Pelletron tandem. LEBT, divided resister system, terminal stripper. The beam time for AMS research has increased to about 42% of the total operation time. Tsukuba AMS system We are able to measure long-lived radioisotopes of 26 Al, Cl and 129 I by employing a molecular pilot beam method that stabilize the terminal voltage with 0.1% accuracy. Main research fields are earth and environmental sciences. Future plans GVM control system New injection beam line (MC-SNICS)

32 Thank you for your kind attention.

33 Appendix

34 26 Al-AMS 120 mag. ΔE-E detector 45 mag. 26 Al 13+ FC AMS ion source 26 MgO - 26 AlO - 27 AlO - deflector(8 ) 2 nd stripper (40μg/cm 2 ) V t =10.2MV 26 Mg 7+ Slit current feedback Inflection mag. 1 st Stripper 26 Mg n+ 26 Al m+ - Full stripping technique: 26 Al 13+ / 27 AlO - [counts/μc] - Pilot beam: 26 MgO - - Beam current of AlO - from Al 2 O 3 sample : 1.5μA The beam transmission of full stripped Al 13+ : 10%. 26 Mg n + (m 12) 26 Al m + (n 13) Switching mag. 26 Mg Al 7+ (77.7 MeV) Analyzing mag.

35 AMS facilities in JAPAN 10 AMS facilities (12 accelerators) Kyushu University Tandem (10MV): 14 C JAEA Tono Tandem (5MV): 14 C Kyoto University Tandem (8MV): 14 C Paleo Labo Co., Ltd. Tandem (500kV): 14 C JAEA Mutsu Tandetron (3MV): 14 C, 129 I Institute of Acceleratory Analysis Ltd. Tandem (3MV): 14 C Tandem (500kV): 14 C NI-TERRA Tandem (5MV): 14 C University of Tsukuba Tandem (12MV): 26 Al, Cl, 129 I Nagoya University Tandetron (3MV): 14 C Tandetron (2.5MV): 14 C MALT, The University of Tokyo Tandem (5MV): 10 Be, 14 C, 26 Al, Cl, 129 I

36 AMS data acquisition and control system

37 Replicated Cl standard measurements Standard sample: Cl/ 35 Cl = It takes 3 minutes for each measurement. The standard deviation of the fluctuation of the Cl/ 35 Cl ratio is kept within ± 3 %.

38 Cl production e n γ e Primary Cosmic Ray γ π ± μ ± π ± n μ ± n π ± π ± n n n μ ± π ± n n Cl (T 1/2 =301 kyr): β-decay Ar (98 %) Natural-Cosmic rays 40 Ar(p, nα) Cl Ar (n, p) Cl atoms/m 2 /s Neutron capture (U, Th) 35 Cl (n, γ) Cl Human activities 35 Cl (n, γ) Cl (44 barn) Nuclear explosion tests in the sea ( ) Atomic power plant, Nuclear fuel cycle facilities, etc.

39 Cl-AMS ΔE Cl 32 counts S Cl / 35 Cl (counts/μc) Standard sample ( Cl/ 35 Cl = ) No. 18 No. 20 No. 18 Blank sample: Cl / 35 Cl= E-ΔE 5 minutes measurement Run No. Reproduction in replicated measurements Cl-AMS (Vt:10MV) Beam energy: Cl MeV Background: Cl/Cl=~ Detection range: Cl/Cl=10-10 ~10-14 Accuracy: ± 3 % ( Cl/Cl~10-12 )

40 Charge state distribution of Cl ions Charge state distribution of 35 Cl and 37 Cl ions after the passage through a carbon. [by Dr. Shima et al.] 1st stripper 9MV 10MV Charge fraction nd stripper Charge fraction F(q) of 90MeV 35 Cl 9+ emerging from a carbon E [MeV] Charge fraction F(q) of 35 Cl 9+ increased 1.5 times from 20% to 30% C- [μg/cm 2 ] The optimum thickness of 2 nd stripper : 12-15μg/cm 2 [F(14+)]

41 Sample preparation Sample (10 20 ml) 30% H 2 O 2 (1 ml) 13 M HNO 3 (1 ml) 0.3 M AgNO 3 (1 ml) Centrifugation (2500 rpm, 10 min) Supernatant Precipitate (AgCl) Sulfur Reduction (2 times) 3 M NH 4 OH (2 ml) sat. Ba(NO 3 ) 2 (3 ml) Filtration (Filter Paper) Sample: AgCl 1 5mg Filtrate ([Ag(NH 3 ) 2 ] + Cl ) 13 M HNO 3 (0.5 ml) Centrifugation (2000 rpm, 15 min) Precipitate (BaSO 4 ) Supernatant Precipitate (AgCl) Washing (with 0.01 M HNO 3, 2 times) Washing (with 99.5% C 2 H 5 OH) Drying (130 C, 3 h) A benzene saturated solution of fullerene (C 60 ) for 12 C 3- pilot beam. [7.6 μl / AgCl: 1 mg]