Positron Probe Microanalyzer (PPMA) facilities at AIST

Transcription

1 Positron Probe Microanalyzer (PPMA) and other accelerator based slow positron facilities at AIST B. E. O Rourke, N. Oshima, A. Kinomura, T. Ohdaira and R. Suzuki National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan 10 th International Workshop on Positron and Positronium Chemistry Smolenice Castle, Slovakia, 7 th Sept 2011

2 AIST Electron Accelerator Facility 300 MeV e - LINAC (1979- ) SCA New e+ beamline (PPMA, PALS) Existing e + facilities (PALS, PPMA, PAES) Slow e + beamline (1988- )

3 AIST LINAC-based Slow Positron Beam PPMA PALS TOF- PAES Ta converter 70 MeV, 100mA peak, 1 s, 100 pps e - Linear Storage Section W moderator slow e+ Bremsstrahlung + Pair Production

4 AIST LINAC-based Slow Positron Beam PPMA PALS TOF- PAES Ta converter Positron / Ion combined Beamline 70 MeV, 100mA peak, 1 s, 100 pps e - Linear Storage Section ion positron W moderator slow e+ Bremsstrahlung + Pair Production sample

5 RI-based PALS 22 Na 1 GBq Counting rate ~4,000 cps Time resolution < 200 ps Time resolution ~250 ps m Kapton Best 通常セットアップ resolution: BaF2 50x50mm 時間分解能 250ps テスト用セットアップ BaF2 40x10mm 時間分解能 155ps 155 ps Normalized counts =385ps Time (ns) 1.5 m Commercially available from FUJI IMVAC Inc.

6 PAES e + Pulsing Apparatus PPMA 6

7 Positron Probe Microanalyzer (PPMA) 7

8 Positron Probe Microanalyzer (PPMA) N. Oshima et al., Radiat. Phys. Chem. 78, 1096 (2009) Buncher Focusing lens 8

9 PALS System for Positron Microbeam PAL spectra with micro beam Normalized Counts 10 0 SiO 2 un-irradiated SiO 2 H + 50 kev Kapton Time(ns) Resolution < 200 ps Diameter: <30 m Counting rate: 1-3k cps for 30 um

10 Positron Probe Microanalyzer (PPMA) x-y stage Objective Lens Remoderator

11 Brightness Enhancement System ~ kev Moderator Reemission of positrons ~ ev Beam diamet ter 10mm 1mm 100μm 10μm Bi Brightness enhancement Magnetic guide(~20m) 1μm k 10k Energy(eV) Extraction Coil Focusing Lens Ni Remoderator N. Oshima, J. Appl. Phys. acceleration (2008) Pulsing system RF

12 Beam Diameter / Time Width of Bunch Pulse Width: 5-10 ns 0.3 ns 0.1 ns Beam 2-3 kcps for PALS Beam Size: ~10 mm (FWHM) ~1 mm (FWHM) ~25 m(fwhm) in solenoid at remoderator at sample Ta SiO 2 J. Appl. Phys. 103, (2008)

13 3-D Mapping of Defects unimplanted a-sio2 Diameter: <30 m Resolution ~200 ps Counting rate: 1-3k cps for 30 m implanted Focused e + beam Mean impl. Depth (Energy) 200 nm (4.7 kev) Appl. Phys. Lett. 94, (2009) Defects created by Ar + and H + H + ion beam Ar + ion beam (50 kev cm -2 ) (150 kev cm -2 ) 30 mesh Scan 350 nm (6.4 kev) Depth 600 nm Rotate 45 o a-sio2 Depth 200 nm Sample 1pixel : 50 μm x 50 μm ( ~1 s/pixel) total:3500pixels 500 nm (7.8 kev) lifetime short long Defects created by H +

14 PPMA Ductile Fractured Iron Sample nominal strain = 0 % 0.5 % 0.5 % 2.9 % 14.7 % gauge chu uck 1 mm V4-V5V5 V7-V10 chuck (PPMA parameters) Beam energy : 25 kev Beam diameter : 50 m Scanning step : 50 m 2 (gauge area) 100 m 2 (chuck area) -ray counts : 5000 / pixel Measurement points : 10,000 / image average positron lifetime 130 ps 180 ps 14

15 Extraction of Slow Positrons to Air 60 I 3 (%) SiO 2 (100nm)/Si in vacuum in air with SiN(30nm) positron beam energy (kev) N. Oshima et al., Appl. Phys. Express 4, (2011)

16 Nanotechnology shared infrastructure Nano Characterization Nano Processing Facility (NPF) Manufacturing Center Research Support Technical Training HR-NMR Electron Microscope MEMS Foundary

17 AIST Electron Accelerator Facility 300 MeV e - LINAC (1979- ) SCA New e+ beamline (PPMA, PALS) Existing e + facilities (PALS, PPMA, PAES) Slow e + beamline (1988- )

18 New Positron Beamline Goal: To increase the speed and efficiency and volume of our PALS and PPMA measurements Current Situation: Under construction. Should be ready for tests with electrons soon and first positrons within this fiscal year (March 2012) PPMA PALS

19 New Positron Beamline PALS PPMA Positron Converter & Moderator Linear Storage Section Concrete Shield 1240 Positron Experimental Room Concrete Wall Accelerator Room

20 New Positron Beamline φ10 PPMA RF Buncher (125MHz) Linear Storage Section Concrete Wall Positron Converter & Moderator Remoderatror RF Buncher (125 MHz)

21 AIST Electron Accelerator Facility 300 MeV e - LINAC (1979- ) SCA New e+ beamline (PPMA, PALS) Existing e + facilities (PALS, PPMA, PAES) Slow e + beamline (1988- )

22 Superconducting Accelerator (SCA) CW or high duty operation 24 h operation Energy gain 7.5 MeV High power (> 10 kw) Recondensor 40K/80K refrigerator He port 80K heat shield 40K heat shield 2905 RF Coupler Nb cavity HOM coupler

23 Current Situation at AIST Current LINAC SCA Module 1 (Present Position) Positron Experimental Room 10 m

24 Initial Set-up Plan Current LINAC New Beamline Positron Convertor and Moderator SCA Module 1 (Present Position) Positron Experimental Room Positron Beamline 10 m

25 Monte Carlo Simulation Step 1: Calculate energy and angular emission distributions of fast e + Step 2: Calculate the depth distribution profile of e + absorbed in W

26 Slow Positron Production e + /10 8 e - ) N ( Current Simulation x 25.6% N = 0.28(E e - 3) N e LLNL LLNL Fit = 1.4(E e - 15) AIST Argonne Mitsubishi Electron Energy, E e (MeV) s s (5 MeV) (70( MeV) ) s s B. E. O Rourke et al., Rev. Sci. Instrum. 82 (2011) (10 MeV) (70 MeV) 0.4% 3%

27 Maximum Slow Positron Yield Ele ectron Cu urrent, I e ( A) K 2500 K 2000 K 10 8 T > 3270 K K K 500 K Electron Energy, E e (MeV) Y (e + /s) B. E. O Rourke et al., Rev. Sci. Instrum. 82 (2011)

28 Beam Heating of the Converter T 0 ( T T )2 l Conduction T b w w Pw r ln( r 2 / r1 ) r 1 Radiation e - T b 4 Pr 2e ( ( T ( r) T r )2 rdr Cylindrical top-hat beam E d I e P w P r

29 Maximum Slow Positron Yield Ele ectron Cu urrent, I e ( A) K 2500 K 2000 K T > 3270 K K 1000 K 500 K Y (e + /s) SCA: 5 15 MeV Electron Energy, E e (MeV) 70 MeV LINAC B. E. O Rourke et al., Rev. Sci. Instrum. 82 (2011)

30 Summary PPMA: PALS measurements possible with a microbeam (30 m) 2-D and 3-D defect imaging (Beam Energy 0 30 kv) Extraction of positron microbeam to air New Positron Beamline: Currently under construction (scheduled completion this fiscal year Mar 2012) Vertical beamlines for PALS and PPMA Initially operated using existing LINAC (70 MeV), in future will be synchronous with SCA Superconducting Accelerator (SCA) High pulse repetition rate, no e+ pulse stretching and chopping Low energy but high current, beam heating in the converter/moderator will be a challenge

31 THANK YOU and thanks to our collaborators; Positron Probe Microanalyzer M. Fujinami (Chiba Uni.) A. Uedono (Tuskuba Uni.) New Positron Beamline Vacuum Products Inc. Superconducting Accelerator N. Hayashizaki (Tokyo Inst. Tech) E. Minehara (Wakasa-WanEnergyRes Wan Res. Centre) TIME Inc.