Intense Slow Positron Source

Intense Slow Positron Source Introduction Science & Frontier Technology Production of e + Competition Proposal Request to EPAC ~ 14 m 10 MeV rhodotron target - collector moderator - buffer gas - trap e+ P. Pérez & A. Rosowsky 1

Introduction Our motivation: detect deviation from gravity in P s or Hbar free-fall make a beam of anti-atoms ( CERN expts.) use few pbar (expensive) use manye + E C ~ ev, D E C ~ 1.5 mev e + factory : today s proposal New applications outside this field for Ne + > 10 9 s -1 P. Pérez & A. Rosowsky 2

Making anti atoms Radiative Recombination (RR) ne 10 8 cm 3 p + + e H p + e + Hbar Laser Induced Radiative Recombination (LIRR) p + + e + hν H + 2hν p + e + + hν Hbar + 2hν 3 Body reactions (3BDY) ne 10 9 cm 3 p + + e + e ± H * + e ± p + e + + e ± Hbar * + e ± e + + e + e ± P s * + e ± Charge exchange with Positronium (CXPS) p + + P s H + e + p + P s Hbar + e H + P s H + e + Hbar + P s Hbar + + e SLAC CERN Matter Anti-matter P. Pérez & A. Rosowsky 3

N.Yamanaka & Y. Kino, Phys. Rev. A 65, 062709 P.K. Biswas, J.Phys. B: At. Mol. Opt. Phys. 34 (2001) 4831 p + + Ps H + e + H + Ps H + e + C.M. 20 KeV p (lab) 10 15 cm 2 10 14 Ps at/cm 3 10 4 Hbar + per incident antiproton 20 KeV p (lab) 10 17 cm 2 P. Pérez & A. Rosowsky 4

Transform all e + into P s in less than 1 ns via 3 body reaction: e + + e + e ± P s * + e ± 20 KeV p ± + P s target H/p = Hbar/p = 0.1 In same P s target H + P s H + e + Hbar + P s Hbar + + e H /H = Hbar + /Hbar =10-3 10 14 Ps at/cm 3 10 4 Hbar + per incident antiproton Lifetime (s) e + lifetime in plasma (s) 10 3 10 2 10 1 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14 ATHENA 2.5 10 8 cm -3 5 mev 20 mev 1 mev direct annihilation Plasma temperature we will be here! 10 12 10 14 plasma density (cm -3 ) 10 10 10 11 10 12 10 13 10 14 10 15 density (cm-3) P. Pérez & A. Rosowsky 5 1 ns 0.1 ns

Layout scheme Greaves-Surko traps Target : aerogel / Si cristal e + trap ( ~ ev ) p + or p trap ( ~20 kev ) S = 1 mm 2 «= 1200 mm L = 1 cm H, H or Hbar, Hbar + ï Free fall expt. Positronium target : e trap ( ~ ev ) Few 10 12 e ± inside 10-2 cm 3 => P s density ~ 10 14 cm -3 several minutes to fill e+ trap P. Pérez & A. Rosowsky 6

Greaves-Surko trap Ne moderator: Ec < 1 MeV ev N 2 buffer gas : ev mev Penning Malmberg trap Rotating wall UC San Diego (7K) ATHENA : 10 8 e + Project to store 10 15 within 3 years 10 12 10 13 e + P. Pérez & A. Rosowsky 7

Fundamental Physics expts Gravity experiment possible with Ps only High Rydberg states of Ps can live ~ 1ms produce thermal Ps atoms (3 km/s max speed) then excited with Doppler-free two photon techniques Ps atoms focused by mirror and converge on 1 mm spot deflection expected from gravity is 50 mm on a 10 m scale rate of slow positrons needed in order to achieve a 5 s measurement in a week of run is ~ 10 9 s -1 BEC Ps A. P. Mills & P.M. Platzman publications 511 KeV g ray laser 3D imaging of molecules P. Pérez & A. Rosowsky 8

Other research & Applications e + e plasmas Astrophysics Feed stellarator for low energy neutral plasma study Relativistic plasmas study on ms to s time scales Cold & bright e + beams materials study High speed electronics and chips (PALS) Positron microscopy Filling of portable trap with 10 12 e + commercial use (UCSD design) «advanced futuristic» projects : energy storage, USAF shuttle propulsion P. Pérez & A. Rosowsky 9

e + Production and Collection Beam energy/intensity : 10 MeV 2~10 ma Target geometry : thin foil at grazing incidence ( 3 degrees) Probability of first interaction (e + & Xrays) Thermal effects : Xrays leak + IR slab effect Large angle collection and selection < 1 MeV P. Pérez & A. Rosowsky 10

Target (2) Study energy deposit as a function of incidence angle Y e beam section 1 mm x 20 mm LINAC 10 MeV e 3 degree Thickness = D equivalent thickness: D = D / sin 3 0 e+ 3 0 D Z e+ e+ e+ X D Tungsten target 20 mm x 20 mm x 50 µm P. Pérez & A. Rosowsky 11

Kinetic energy at target exit positrons electrons Energy (GeV) Energy (GeV) P. Pérez & A. Rosowsky 12

Energy versus angle Production point At target exit angle Kinetic energy (GeV) Kinetic energy (GeV) P. Pérez & A. Rosowsky 13

Magnetic Bulb B target e + e + e - B B dump x target e + P. Pérez & A. Rosowsky 14

Collection Setup WALL SHIELD MAGNET H1 QUADRUPOLE TARGET DUMP MAGNET H2 HELMOLTZ GUIDING TUBE 00 00 00 11 11 11 20 cm 50 cm 40 cm 1 m count e + here 00 11 11 00 P. Pérez & A. Rosowsky 15

Simulation and engineering x x 10 cm 10 cm z 10 cm P. Pérez & A. Rosowsky 16 z

Positrons y z x P. Pérez & A. Rosowsky 17

electrons x z 10 cm P. Pérez & A. Rosowsky 18

3D view P. Pérez & A. Rosowsky 19

e+ position in (y, z) planes Before 4-poles X = 3 cm X = 200 cm P. Pérez & A. Rosowsky 20

energy versus radius at x = 200 cm positrons Radius (cm) electrons Energy (GeV) Energy (GeV) P. Pérez & A. Rosowsky 21

Positrons radius at x = 200 cm Kinetic energy < 1 MeV All kinetic energies Radius (cm) Radius (cm) P. Pérez & A. Rosowsky 22

Target e - soldering test on Tungsten 50 mm 40 kv / 20 ma on 20 mm 2 not perforated at 15 ma Working hypothesis: 1 k W / cm 2 3100 K Test with high intensity beam from IBA foreseen T rise, evaporation P. Pérez & A. Rosowsky 23

Target (2) Study energy deposit as a function of incidence angle Y e beam section 1 mm x 20 mm LINAC 10 MeV e 3 degree Thickness = D equivalent thickness: D = D / sin 3 0 e+ 3 0 D Z e+ e+ e+ X D Tungsten target 20 mm x 20 mm x 50 µm P. Pérez & A. Rosowsky 24

Target (3) 10 4 e - track length inside targets of 1mm equivalent thickness 10 3 3 0 10 2 90 0 <L> ( cm) ( cm) 3 0 0.11 0.11 rms 90 0 0.53 0.48 10 1-0.5 0 0.5 1 1.5 2 2.5 3 track length (cm) P. Pérez & A. Rosowsky 25

Energy Deposit in 1cm 2 Target E(e - ) = 10 MeV Simulation with GEANT/EGS Power (W) 10000 9000 8000 7000 6000 E=10MeV puissance deposee pour 1mA de e Deposited power for 1 ma - 90 0 Current (ma) 10 2 10 E=10MeV courant d e - pour 1kW puissance deposee I MAX for 1 kw deposited 5000 4000 3000 2000 1000 0 0 1000 2000 3000 4000 5000 4.5 kw/ma 1.7 kw/ma 3 0 1 10-1 0.59 ma 0.22 ma 0 1000 2000 3000 4000 5000 D (mm) D (m m) 90 0 P. Pérez & A. Rosowsky 26 3 0

Production Rate (1) 10 7 electrons on 1 cm 2 target Ne + 25000 22500 20000 17500 E=10MeV nombre de e + a l avant pour 10 7 e - sur la cible e + forward 3 0 Ne + 8000 7000 6000 E=10MeV nombre de e + de moins de 1 MeV a l avant pour 10 7 e - sur la cible Ee + <1 MeV 3 0 15000 12500 5000 90 0 4000 90 0 10000 7500 5000 2500 3000 ~ 15000 / 10 7 = 1.5 10-3 2000 ~ 3500 / 10 7 = 3.5 10-4 1000 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 D (m m) D (m m) P. Pérez & A. Rosowsky 27

Production Rate (2) X 10 9 Ne + (s -1 ) x 10 9 8000 7000 6000 5000 Power deposited in 1 cm 2 target = 1 kw E=10MeV taux de e + a l avant pour 1kW depose dans la cible e + forward Ne + (s -1 ) X x 10 9 9 2000 E=10MeV taux de e + de moins de 1 MeV a l avant pour 1kW depose dans la cible 1800 1600 1400 1200 Ee + <1 MeV 3 0 30 1.4 10 12 4000 1000 3000 2000 1000 800 600 400 90 0 90 0 200 0.6 10 12 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 D (m m) D (m m) P. Pérez & A. Rosowsky 28

Production For 1 cm 2 of target D = 1mm Limit 1 kw / cm 2 90 80 70 Normalization to same number of e - generated 90 0 in units of 10 12 s -1 60 Imax Ne + Ne + (<1MeV) 50 40 3 0 0.58 ma 4.6 1.1 30 3 0 90 0 0.25 ma 2.5 0.55 20 10 0.58 ma 2.3 ma for 4 cm 2 0 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 x 10-2 1 2 3 4 5 Ee+ (MeV) P. Pérez & A. Rosowsky 29

Collection efficiency Fraction of e + at exit plane inside circle of radius 5 or 2 cm centered on axis 1 r = 5 cm 1 r = 2 cm 0.9 E < 600 KeV 0.9 0.8 with quad 0.8 e 5 0.7 0.6 e 2 0.7 0.6 slit shaped beam 0.5 0.4 E < 1 MeV no quad 0.5 0.4 1 x 4 cm 0.3 0.2 0.3 0.2 2 x 2 cm 0.1 0.1 0 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0.2 0.4 0.6 0.8 1 1.2 1.4 transverse radius of e + source at target level (cm) P. Pérez & A. Rosowsky 30

Collected Positron Rates (2m from target) e+ produced as much as possible near axis is best for production and collection (e + rates in units of 10 12 s -1 ) R e e + coll = 5 cm rate 5 50 all e + at exit plane forward E <1 MeV 20% 52% 4.2 2.7 40 E < 600 KeV 60% 1.3 30 20 10 0 R < 2 cm R < 5 cm 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 E (MeV) R coll = 2 cm forward E <1 MeV E < 600 KeV 8% 20% 30% e + rate 1.6 1.1 0.6 P. Pérez & A. Rosowsky 31 e 2

Electron and photon fluxes Two possible setups with same e + output Beam and coils on same axis e - Target and downstream coils on same axis e - P. Pérez & A. Rosowsky 32

Fluxes of electrons and photons I = 2.3 ma Setup 1 Setup 2 R = 1 cm 5 W 10 W R = 2 cm 140 W 45 W R = 3 cm 450 W 80 W R = 4 cm 1.5 kw 110 W at exit plane 10 10 Power (kw) 9 8 7 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 Power (kw) 9 8 7 0.25 0.225 0.2 0.175 0.15 0.125 0.1 0.075 6 0.2 0.1 6 0.05 0.025 5 0 200 210 220 230 240 250 260 270 280 5 0 200 210 220 230 240 250 260 270 280 plots for 1 ma 4 3 2 1 0 4 Setup 1 Setup 2 0 50 100 150 200 250 300 X (along coils axis) (cm) X (along coils axis) (cm) P. Pérez & A. Rosowsky 33 3 2 1 0 0 50 100 150 200 250 300

A very first design of a 2D expander/uniformizer F. Meot and T. Daniel, NIM, A 379 (1996) 196-205. b (m) Postprocessor/Zgoubi NoDate... Z (m) vs. Y 0.01 0.005 Z (m) 0.0 -.005 -.01 -.01 -.005 0.0 0.005 0.01 Y (m) x (m) P. Pérez & A. Rosowsky 34

Design differences (1) Rossendorf / Aarhus converter e - extraction lenses trap EPOS design + trap MeV e + W moderator E(decel.) dump 1.5 ev e + E (2-5 kv) converter Proposed design MeV e + e - efficiency Tungsten Neon 10-4 10-2 trap temperature room 7K Ne moderator 1.5 ev e + P. Pérez & A. Rosowsky 35

Design differences (2) Original EPOS design: 40 MeV, 0.25 ma, ~CW Linac Pt or W moderator, 3.5 mm Pt target Neutron activation Collection efficiency before trap 20% Expected Rate before trap 1.6 10 8 s -1 At 10 MeV, 2.5 ma 1mm target = 0.8 10 8 s -1 Proposed design: 10 MeV, 2.5 ma, CW Ne Moderator, thin W target Collection efficiency before trap 20% Expected rate before trap 1.1 10 10 s -1 E (MeV) I(mA) Mod. Activ. L wall Rate 40 0.25 Pt yes 30m 3m 1.6 10 8 10 2.5 W no 3m 2m 0.8 10 8 10 2.5 Ne no 3m 2m 10 10 P. Pérez & A. Rosowsky 36

Other designs Thermal neutron capture: 113 Cd(n,g) 114 Cd s = 26000 barn!! By nuclear research reactor FRM2 in Munich (Germany) can reach 10 10 s -1 Building size: 40 m x 40 m x 30 m P. Pérez & A. Rosowsky 37

Scientific Goals Gravity and spectroscopy with P s H Hbar Astrophysics in vitro 3D molecule imaging P s BEC and 511 KeV Laser Applied technology : positron microscope P. Pérez & A. Rosowsky 38

Proposal: best ingredients.. e + facility : Ne + > 10 9 s -1 ~ 14 m fundamental interaction physics : HEP lab e beam expertise and beam research 10 MeV rhodotron SR radiation control infrastructure Interdisciplinary lab Location near trap development target - collector moderator - buffer gas - trap e+ P. Pérez & A. Rosowsky 39

Ressource Impacts Building : new ~ 2.5 M$ refurbished ~ x00 k$ Target-collection Injection ~ 400 k$ e- machine : Rhodotron ~ 2.5 M$ Linac ~ 300 k$ Infrastructure : 250 kw Water cooling Radiation control, safety Parallel project UC San Diego Moderator Buffer gas trap ~ 500 k$ P. Pérez & A. Rosowsky 40

Requests Winter workshop: Start interdisciplinary community Start SLAC - Saclay project collaboration Trigger other institutes interest EPAC feed back: encourage TDR for june 2004 EPAC P. Pérez & A. Rosowsky 41