Intense Slow Positron Source

Transcription

1 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

2 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

3 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

4 N.Yamanaka & Y. Kino, Phys. Rev. A 65, 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) cm Ps at/cm Hbar + per incident antiproton 20 KeV p (lab) cm 2 P. Pérez & A. Rosowsky 4

5 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 = Ps at/cm Hbar + per incident antiproton Lifetime (s) e + lifetime in plasma (s) ATHENA cm -3 5 mev 20 mev 1 mev direct annihilation Plasma temperature we will be here! plasma density (cm -3 ) density (cm-3) P. Pérez & A. Rosowsky 5 1 ns 0.1 ns

6 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 e ± inside 10-2 cm 3 => P s density ~ cm -3 several minutes to fill e+ trap P. Pérez & A. Rosowsky 6

7 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 within 3 years e + P. Pérez & A. Rosowsky 7

8 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

9 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 e + commercial use (UCSD design) «advanced futuristic» projects : energy storage, USAF shuttle propulsion P. Pérez & A. Rosowsky 9

10 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

11 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

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

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

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

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

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

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

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

19 3D view P. Pérez & A. Rosowsky 19

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

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

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

23 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 K Test with high intensity beam from IBA foreseen T rise, evaporation P. Pérez & A. Rosowsky 23

24 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

25 Target (3) 10 4 e - track length inside targets of 1mm equivalent thickness <L> ( cm) ( cm) rms track length (cm) P. Pérez & A. Rosowsky 25

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

27 Production Rate (1) 10 7 electrons on 1 cm 2 target Ne E=10MeV nombre de e + a l avant pour 10 7 e - sur la cible e + forward 3 0 Ne E=10MeV nombre de e + de moins de 1 MeV a l avant pour 10 7 e - sur la cible Ee + <1 MeV ~ / 10 7 = ~ 3500 / 10 7 = D (m m) D (m m) P. Pérez & A. Rosowsky 27

28 Production Rate (2) X 10 9 Ne + (s -1 ) x 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 E=10MeV taux de e + de moins de 1 MeV a l avant pour 1kW depose dans la cible Ee + <1 MeV D (m m) D (m m) P. Pérez & A. Rosowsky 28

29 Production For 1 cm 2 of target D = 1mm Limit 1 kw / cm Normalization to same number of e - generated 90 0 in units of s Imax Ne + Ne + (<1MeV) ma ma ma 2.3 ma for 4 cm x Ee+ (MeV) P. Pérez & A. Rosowsky 29

30 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 with quad 0.8 e e slit shaped beam E < 1 MeV no quad x 4 cm x 2 cm transverse radius of e + source at target level (cm) P. Pérez & A. Rosowsky 30

31 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 s -1 ) R e e + coll = 5 cm rate 5 50 all e + at exit plane forward E <1 MeV 20% 52% E < 600 KeV 60% R < 2 cm R < 5 cm E (MeV) R coll = 2 cm forward E <1 MeV E < 600 KeV 8% 20% 30% e + rate P. Pérez & A. Rosowsky 31 e 2

32 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

33 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 Power (kw) Power (kw) plots for 1 ma Setup 1 Setup X (along coils axis) (cm) X (along coils axis) (cm) P. Pérez & A. Rosowsky

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

35 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 trap temperature room 7K Ne moderator 1.5 ev e + P. Pérez & A. Rosowsky 35

36 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 s -1 At 10 MeV, 2.5 ma 1mm target = s -1 Proposed design: 10 MeV, 2.5 ma, CW Ne Moderator, thin W target Collection efficiency before trap 20% Expected rate before trap s -1 E (MeV) I(mA) Mod. Activ. L wall Rate Pt yes 30m 3m W no 3m 2m Ne no 3m 2m P. Pérez & A. Rosowsky 36

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

38 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

39 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

40 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

41 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