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 (PS)

En = -13.6/2n2, r = 2 rb = 0.1 nm Singlet state, (2γ, 4γ ...) τs = 125 ps

1S0 para-positronium (p-Ps)

Triplet state, (3γ, 5γ ...) = 142 ns

3S1 ortho-positronium (o-Ps)

Friday, September 21, 2012

FUNDAMENTAL PHYSICS MIRROR DARK MATTER

• -Ps go to invisible mode

Lagrangian ∼ ε FμνF’μν ; ΔE = 2hεf experimental upper limit for ε < 2 10-7 Oscillation in vacuum ΓSM -> o-Ps decay rate, Ω = 2πεf Br(o-Ps->invis.) = 210-7 , ε = 410-9

DAMA/NaI

R.Foot, Phys.Rev.D78,043529,2008

Friday, September 21, 2012

AN EXPERIMENT TO SEARCH FOR MIRROR DARK MATTER

• -Ps -> invisible mode

Background level - 10-7 104 e+/s, Texp- 106 s

P.Crivelli et al. “A new exp. to search for mirror dark matter”, arXiv:1005.4802.v4[hep-ex] 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

σ2γ = π r02 c/v, r0=2.8 fm λ = σ2γ v ne [1/s] sinθ ≅ pt /me c ΔEγ= pp c /2

V.I. Grafutin, E.P. Prokopiev, UFN 172, 1

Friday, September 21, 2012

POROSITY MEASUREMENT

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

CERN(MCP)

Friday, September 21, 2012

POSITRON SOURCES

Radioactive source 22Na -> 22Ne + e+ + γ(1.28), 2.6y

52Co (72d), 64Cu (13h) 18F (92h)

Electron accelerator with energy 8 - 260 МэВ Neutron reactor ( γ , n-> γ) γ (Eγ>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 μA, pulse 30ps, apart repeatedly 768 ps, slow positron beam - 1010 e+/

• sec. Duty factor 1

Pulsed electron , duty factor ∼10-2 -10-4: Japan, Tsukuba AIST LINAC 8-70 MeV, 100-10 μA, slow positron beam - 108 e+/sec Germany, MAMI microtron, 170 MeV, 75 μA, slow positron beam - 108 e+/sec ; Giessen LINAC, 35 MeV, 100 μA, slow positron beam - 108 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 10μA, 100 Hz, pulse 1 μs

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 108 e+/s

Friday, September 21, 2012

ARGONNE SLOW POSITRON SOURCE

ANL LINAC 15 MeV, pulse 30ps, apart repeatedly 768 ps, 200 μA, 35 kW Proposed combined target, 10 W plate d = 0.4 mm, L = 10 mm, gap = 1mm, θ=10o Target eff. - 10-3 Moderator W eff. - 10-3 Slow e+ - 109 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 GEANT3 simulation W target - 1.5 mm, r=0.5 cm Setup with B field 0.6 - 0.3 T Cone moderator - 4 μm W foil e+ yield - 1.8x10-3 e+/ e e+ - stop efficiency - 1.5x10-4/e

Beam e-

Moderator Target

Friday, September 21, 2012

SLOW POSITRON YIELD FROM THIN W FOIL

e+ leave W surface Te+ = 2.8 eV εW = 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 λd Probability P(λd) = 1 - exp (-λd /λT), λT - total mean path 1/λT = 1/λc + 1/λa , λc - collision length, λa - 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 μA (6x1013 e-) Yield e+/e increased 10 times Intensity of e+ = 1.2x108 (2x10-6 x 6x1013)

Beam e- MAMI Mainz

Target Moderator

Friday, September 21, 2012