POSITRON SOURCE FOR ANNIHILATION SPECTROSCOPY R.M. Djilkiabev, - PowerPoint PPT Presentation

POSITRON SOURCE FOR ANNIHILATION SPECTROSCOPY R.M. Djilkiabev, INR, Moscow Friday, September 21, 2012

SLOW POSITRON SOURCE FOR FUNDAMENTAL AND APPLIED PHYSICS Positronium (e + e - ) is a simplest atom and ideal system to probe a new physics beyond the Standard model (SM) Mirror world model is one of the possible extensions of SM of particle physics Precision measurements of o-Ps decay time in vacuum. Precision of QED calculation is higher of two order of magnitude then experimental level Positron annihilation spectroscopy (PAS) is a unique method to define material defect size and concentration, near surface, in nano meter scale Friday, September 21, 2012

POSITRONIUM (P S ) E n = -13.6/2n 2 , r = 2 r b = 0.1 nm Singlet state, (2 γ , 4 γ ...) τ s = 125 ps 1 S 0 para-positronium (p-P s ) Triplet state, (3 γ , 5 γ ...) = 142 ns 3 S 1 ortho-positronium (o-P s ) Friday, September 21, 2012

FUNDAMENTAL PHYSICS MIRROR DARK MATTER o-Ps go to invisible mode Lagrangian ∼ ε F μν F’ μν ; Δ E = 2h ε f experimental upper limit for ε < 2 10 -7 Oscillation in vacuum DAMA/NaI Γ SM -> o-Ps decay rate, Ω = 2 π ε f R.Foot, Phys.Rev.D78,043529,2008 Br(o-Ps->invis.) = 210 -7 , ε = 410 -9 Friday, September 21, 2012

AN EXPERIMENT TO SEARCH FOR MIRROR DARK MATTER P.Crivelli et al. “A new exp. to search for mirror o-Ps -> invisible mode dark matter”, arXiv:1005.4802.v4[hep-ex] Background level - 10 -7 10 4 e + /s, T exp - 10 6 s PhysRevD.75.032004,2007 Signal Friday, September 21, 2012

APPLIED PHYSICS POSITRON SPECTROSCOPY OM - optical microscope, TEM - transmission electron microscope, nS - neutron scattering, XRS - x-ray scattering with synchrotron radiation, STM - scanning tunneling microscope, AFM - atomic force microscope Web site www.positronsystems.com Friday, September 21, 2012

POSITRON ANNIHILATION SPECTROSCOPY σ 2 γ = π r 02 c/v, r 0 =2.8 fm λ = σ 2 γ v n e [1/s] sin θ ≅ p t /m e c Δ E γ = p p c /2 V.I. Grafutin, E.P. Prokopiev, UFN 172, 1 Friday, September 21, 2012

POROSITY MEASUREMENT CERN(MCP) А . С . Белов , А . И . Берлев , С . Н . Гниненко и др . ” Технологический комплекс позитронной аннигиляционной спектроскопии для исследования наноструктурных материалов и неразрушающего контроля , диагностики и анализа присутствующих в них примесях ”, Москва , 2011 Friday, September 21, 2012

POSITRON SOURCES Radioactive source 22 Na -> 22 Ne + e + + γ (1.28), 2.6y 52 Co (72d), 64 Cu (13h) 18 F (92h) Electron accelerator with energy 8 - 260 МэВ Neutron reactor ( γ , n-> γ ) γ (E γ >1.02 MeV) -> e + + e - Friday, September 21, 2012

SLOW POSITRON BEAMS Continuous electron accelerator, duty factor ∼ 1: Argonne Nat. Lab, LINAC 15 MeV, 200 μ A, pulse 30ps, apart repeatedly 768 ps, slow positron beam - 10 10 e + / sec. Duty factor 1 Pulsed electron , duty factor ∼ 10 -2 -10 -4 : Japan, Tsukuba AIST LINAC 8-70 MeV, 100-10 μ A, slow positron beam - 10 8 e + /sec Germany, MAMI microtron, 170 MeV, 75 μ A, slow positron beam - 10 8 e + /sec ; Giessen LINAC, 35 MeV, 100 μ A, slow positron beam - 10 8 e + /sec Friday, September 21, 2012

ELECTRON ENERGY FOR POSITRON SOURCE Minimal e - energy? Target - W, Ta 6 Mev e - , Saclay, France Friday, September 21, 2012

AIST LINAC SLOW POSITRON SOURCE AIST LINAC 70 MeV 10 μ A, 100 Hz, pulse 1 μ s B.E. O’Rourke et al., ‘AIST simulation of slow positron production ...’, arXiv: 1102.1220v2, 10 May 2011, Advanced Industrial Science and Technology (AIST),Japan Friday, September 21, 2012

AIST LINAC SLOW POSITRON SOURCE Expected e + source intensity A NEW SOURCE 10 8 e + /s Friday, September 21, 2012

ARGONNE SLOW POSITRON SOURCE ANL LINAC 15 MeV, pulse 30ps, apart repeatedly 768 ps, 200 μ A, 35 kW Proposed combined target, 10 W plate d = 0.4 mm, L = 10 mm, gap = 1mm, θ =10 o Target eff. - 10 -3 Moderator W eff. - 10 -3 Slow e + - 10 9 e + /s H.M. Chen et al. Applied Surface Science 252, 3159, 2006 Friday, September 21, 2012

A NEW POSITRON SOURCE WITH A MAGNETIC TRAP Electron energy - 8 MeV Beam e - GEANT3 simulation Moderator W target - 1.5 mm, r=0.5 cm Target Setup with B field 0.6 - 0.3 T Cone moderator - 4 μ m W foil e + yield - 1.8x10 -3 e + / e e + - stop efficiency - 1.5x10 -4 /e Friday, September 21, 2012

SLOW POSITRON YIELD FROM THIN W FOIL e + leave W surface T e+ = 2.8 eV ε W = 0.05/4 = 1.25x10 -2 Slow positron yield = 1.5x10 -4 x1.25x10 -2 =2x10 -6 e + /e Thermolized positron is transported by a small length λ d Probability P( λ d ) = 1 - exp (- λ d / λ T ), λ T - total mean path 1/ λ T = 1/ λ c + 1/ λ a , λ c - collision length, λ a - anni.length Escaping profile P(z) = f(z) exp(-z/L) 0.6 T 0.6 T Friday, September 21, 2012

SLOW POSITRON BEAM WITH A MAGNETIC TRAP Electron beam 8 MeV, 10 μ A (6x10 13 e - ) Yield e + /e increased 10 times Intensity of e + = 1.2x10 8 (2x10 -6 x 6x10 13 ) Beam e - MAMI Mainz Target Moderator Friday, September 21, 2012