Department of Physics, Techno India Batanagar (Techno India Group), Kolkata , West Bengal, India.

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1 Department of Physics, Techno India Batanagar (Techno India Group), Kolkata , West Bengal, India. Visiting SINP, IIEST Kolkata, India. nn.mondal2011@gmail.com, nagendra.n.mondal@biemsindia.org

2 Outline of the Talk

Historic Cloud Chamber Experiment in 1932.

3 + (90%) e + 511 kev N Slow e + beam N 511 kev (10%) EC

3 Predicted by P. A. M. Dirac and Experimentally found by Carl Anderson in a Historic Cloud Chamber Experiment in β + -decay process in Radio Isotope: p n + e + + ν 22 Na 3 + (90%) e kev N Slow e + beam N 511 kev (10%) EC MeV 511 kev MeV 0 20 Ne + Half-life 2.6 Y, Good for slow e + beam. e + distribution 550 kev E

4 Fission reaction in Atomic Reactor: n + U U Ba + 89 Kr + 3 n + E γ 177 MeV E γ 177 MeV e+ Moderator Slow positron beam e- Target material Fusion Reaction in the Stars/reactor: 1 1H + 1H 1 H e + + ν MeV H + 1H 2He + γ MeV He + 2He 2He H MeV

2. Accelerator based e + Source The Stanford

housed on campus below the Hansen Labs until 2007.

Photon Factory e +, e - beam lines Compact

5 2. Accelerator based e + Source The Stanford University superconducting linear accelerator, housed on campus below the Hansen Labs until This facility is separate from SLAC KEK in Japan, Photon Factory e +, e - beam lines Compact Cyclotron based e + SHI, Japan Curtsey: Google, Wikipedia

6 Cost effective Independent User friendly Positron Source: 22 Na Source Strength: 150 mci Half-life: 2.6 years UHV system: 10-9 torr Moderator: Single crystal W Moderator efficiency: 10-4 Positron pulsing and guiding System Time-of-Flight (TOF) Spectrometer Detectors: NaI(Tl) scintillators Target Chamber: Ps+Laser scattering Cr:LiSAF laser: Wavelength- 256 nm

7 No. of Detectors: 12 NaI(Tl): from BICRON PMT: from HAMAMATSU Pb Thickness: 4.6 cm W Thickness: 2.5 cm PMT NaI Sample Slit gap : 2 mm Positron beam intensity : 10 6 e + /s Position resolution: 1.5 mm Target sample: Single crystal W e + beam Pb ops W Micrometer TOF Spectrometer

Names & Places Contact persons 1. EPOS, Dresden Prof. Krause- Rehberg Positron Sources Beam Energy 40 MeV e - Linac 0.

Stoeffl Pelletron, 3 MeV 1 50 kev 300, 20 MHz Defects of materials, CDBS, PAS, etc. 3. KEK-B Factory, Tsukuba 4. Delft Reactor Amsterdam 5. MRR-FRM-II, Munich 6. TOPS, Tokyo Dr. T. Kumita, *Dr. N.

8 Names & Places Contact persons 1. EPOS, Dresden Prof. Krause- Rehberg Positron Sources Beam Energy 40 MeV e - Linac kev Moderated: 10 9 Beam I: e + /sec Applications and Bunched: 10 6 Defects of materials, AMOC, CDBS, PACS etc. 2. LLNL, Livermore Dr. W. Stoeffl Pelletron, 3 MeV 1 50 kev 300, 20 MHz Defects of materials, CDBS, PAS, etc. 3. KEK-B Factory, Tsukuba 4. Delft Reactor Amsterdam 5. MRR-FRM-II, Munich 6. TOPS, Tokyo Dr. T. Kumita, *Dr. N.N. Mondal Dr. T. Kurihara 2.5 GeV e - Linac kev D-ACAR, TOF, Spin polarization Prof. P. J. Schultz Reactor based 1 ev 40 kev D-ACAR, 2D-Doppler, Depth profile. Prof. G. Kogel Reactor based 100 ev Positron microprobe, defect concentration 22 Na (150 mci) 1eV 250 kev 10 6 BEC, Laser cooling, TOF, defects, polarization 7. GU, Tokyo Dr. I. Kanazawa 22 Na (3 mci) 30 ev 10 3 Vacancy-type defects 8. Bonn University Dr. K. Maier 22 Na (10 mci) 150 ev 10 3 Surface and dislocation of materials 9. TUS, Tokyo Dr. Y. Nagashima 22 Na (740 MBq) 100 ev 10 5 Ps-, moderator, defects of materials. 10. SHI, Tokyo Dr. M. Hirose Compact Cyclotron kev 10 6 Commercial purpose, surface, interface,polarization.

9 E + Defect studies of materials Ref. : Prof. R. Krause-Rehberg Alkali borosilicate Thermalize e Positron + glass source T: o C 511 kev VYCOR-Process 511 kev Extraction: HCl/NaOH E + E b CPG (controlled pore glass) Defects

10 Surface states Energy (ev) Thermal e + Incident e + Thermal Ps (mev) Energetic Ps a few ev -φ free e + - φ + 0 Ps Z Inside material Vacuum Ref: S. Chu et.al; Phys. Rev. B 23, 2060 (1981)

12 MC simulation for 1 ev and 3 ev Ps and their measurements TOF -MCS, N. N. Mondal & TOF Expt., Y. Nagashima (Physical Review B). 12

13 dσ/de e+ (mb/mev) High intensity polarized positron source (a) Polarized e + source for JLC project CO 2 Laser (λ= 10.6 μm, E =0.117 ev e- beam 5.8 GeV γ-ray, E max =60 MeV Principle of polarized e+ source: Thin target, W 6.67 msec (ν =150 Hz) e-e+ pair creation e- e e+ energy (MeV)

14 Requirements of the JLC beam Configuration of the polarized e+ Source for the JLC project CO 2 Lasers 3 GeV Linac BC 2.8 GeV Linac Capture section 1.98 GeV Pre-DR BC RF Gun 3 GeV DR e- beam 5.8 GeV Collision points (Parabolic mirrors) γ-ray Conversion target 1.98 GeV Linac 1.98 GeV DR

15 Atomic density [/cm3] BEC Rb H Ps No-BEC Temperature [K]

16 Laser Prof. A.P. Mills Riverside, USA, in 2010 TMU, Japan, 2002

Monte Carlo Simulation based on GEANT View of ortho-positronium decay points 200 100 0 5 4 3 2 1 Y-position (cm) 0-1 -2-3 -4-5 -5-4 -3-2 -1 0 1 2 X-position (cm) 3 4 5 Position-sensitive Gamma-ray

17 Monte Carlo Simulation based on GEANT View of ortho-positronium decay points Y-position (cm) X-position (cm) Position-sensitive Gamma-ray detectors system is used to visualize The laser cooled ortho-ps. Spatial resolution is 2 mm. It is an ideal system for imaging PsBEC N.N. Mondal, Nucl. Inst. and Meth. in Phys. Res. A (2002).

18 Acknowledgement Author is Pleased to Acknowledge: (mentor of Doctoral course), and of Postdoctoral course) (mentors (Teacher of In-course subjects), for their sincere guidance and encouragement of advanced researches in High Energy Physics and Material Science.

? Physics with many Positrons

Varenna Summer School July 2009? Physics with many Positrons Positron Sources & Positron Beams Christoph Hugenschmidt Technische Universität München What is many? Galaxy: 1.5 10 43 e + /s! = 1 lake + 1