Intense Slow Positron Source

Intense Slow Positron Source Nucl. Inst. Meth. A 532 (2004) 523-532. ~ 14 m 10 MeV Linac 10 MeV rhodotron beam dump target - collector target - collector moderator - buffer gas - trap e+ 18/03/2005 P. Pérez & A. Rosowsky 1

Intense Slow Positron Source Introduction Geometry, heat inside target, e + production rate Collection e - spread, e - dump e - beam, e + e - separation, rotating coils 18/03/2005 P. Pérez & A. Rosowsky 2

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 + e - leak Large angle collection and selection < 1 MeV 18/03/2005 P. Pérez & A. Rosowsky 3

Thin Target at Grazing Angle 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 18/03/2005 P. Pérez & A. Rosowsky 4

Track Length inside Target 10 4 e - track length inside targets of 1mm equivalent thickness 10 3 3 0 10 2 90 0 <L> rms ( cm) ( cm) 3 0 0.11 0.11 90 0 0.53 0.48 10 1-0.5 0 0.5 1 1.5 2 2.5 3 track length (cm) 18/03/2005 P. Pérez & A. Rosowsky 5

Kinetic energy at target exit positrons electrons Energy (GeV) 2004 Energy (GeV) 18/03/2005 P. Pérez & A. Rosowsky 6

Target e - soldering test on Tungsten 50 μm 40 kv / 20 ma on 20 mm 2 not perforated at 15 ma Melting limit: 4 kw / cm 2 Working hypothesis: 2 kw / cm 2 Study hypothesis: 1 kw / cm 2 Test with high intensity beam from IBA foreseen T rise, evaporation 18/03/2005 P. Pérez & A. Rosowsky 7

Electron welding tests Illuminated area = 0.2 cm 2 60 40 KV 2250 30 50 μm 1000 50 2000 25 800 1750 MAX (ma) I 40 30 20 1500 1250 1000 750 Power (W) I MAX (ma) 20 15 10 600 400 Power (W) 10 500 250 5 I MAX Power 200 0 10-2 10-1 1 Thickness (mm) 0 0 20 25 30 35 40 45 50 55 60 0 Voltage (KV) 18/03/2005 P. Pérez & A. Rosowsky 8

Input e - energy comparisons Rule of the game: Target sustains 1 KW continuous deposited power per cm 2 Goal: optimize rate of e + with E e+ < 1 MeV Input variables: E = e - energy, I = e - current, θ = e - incidence angle on target, D = target equivalent thickness Generate e - Power deposited in target & e + Production rate = f (E, I, D, θ) Limit current I Optimal production rate Here try 2 values for E (10 and 100 MeV) and θ (3 and 90 degrees) 18/03/2005 P. Pérez & A. Rosowsky 9

Energy Deposit in 1cm 2 Target Simulation with GEANT Power (W) 10000 9000 8000 7000 6000 E(e - ) = 10 MeV E=10MeV puissance deposee pour 1mA de e Deposited power for 1 ma - 90 0 50000 45000 40000 35000 30000 E(e - ) = 100 MeV E=100MeV puissance deposee pour 1mA de e Deposited power for 1 ma - 90 0 5000 4000 4.5 kw/ma 25000 20000 3000 2000 1000 0 1.7 kw/ma 3 0 0 1000 2000 3000 4000 5000 0 0 2000 4000 6000 8000 10000 D (μm) D (μm) 18/03/2005 P. Pérez & A. Rosowsky 10 15000 10000 5000 4 kw/ma 3 0

Maximum input current Simulation with GEANT Current (ma) 10 2 10 E(e - ) = 10 MeV E=10MeV courant d e - pour 1kW puissance deposee I MAX for 1 kw deposited Current (ma) 10 1 E(e - ) = 100 MeV E=100MeV courant d e - pour 1kW puissance deposee I MAX for 1 kw deposited 0.3 ma 1 0.59 ma 3 0 10-1 3 0 10-1 0.22 ma 90 0 90 0 0 1000 2000 3000 4000 5000 D (μm) 10-2 0 2000 4000 6000 8000 10000 D (μm) 18/03/2005 P. Pérez & A. Rosowsky 11

Production Rate (forward) 10 7 electrons on 1 cm 2 target Ne + 25000 22500 20000 17500 E(e - ) = 10 MeV e + forward E=10MeV nombre de e + a l avant pour 10 7 e - sur la cible 3 0 Ne + X x 10 3 3 4000 3500 3000 E(e - ) = 100 MeV e + forward E=100MeV nombre de e + a l avant pour 10 7 e - sur la cible 3 0 15000 2500 12500 90 0 90 0 2000 10000 ~ 15000 / 10 7 = 1.5 10-3 1500 7500 5000 2500 1000 500 ~ 9 10 5 / 10 7 = 0.09 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 D (μm) D (μm) 18/03/2005 P. Pérez & A. Rosowsky 12

Production Rate (E e+ <1 MeV) 10 7 electrons on 1 cm 2 target Ne + 8000 7000 6000 E(e - ) = 10 MeV Ee + <1 MeV E=10MeV nombre de e + de moins de 1 MeV a l avant pour 10 7 e - sur la cible 3 0 Ne + X 10 2 x 10 2 1400 1200 E(e - ) = 100 MeV E=100MeV nombre de e + de moins de 1 MeV a l avant pour 10 7 e - sur la cible Ee + <1 MeV 3 0 5000 1000 4000 3000 2000 90 0 ~ 3500 / 10 7 = 3.5 10-4 800 600 400 ~ 4 10 4 / 10 7 = 4 10-3 90 0 1000 200 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 D (μm) D (μm) 18/03/2005 P. Pérez & A. Rosowsky 13

Optimal Production Rates (forward) Power deposited in 1 cm 2 target = 1 kw Ne + (s -1 ) X 10 9 x 10 9 8000 7000 6000 5000 E(e - ) = 10 MeV E=10MeV taux de e + a l avant pour 1kW depose dans la cible e + forward 5.5 10 12 3 0 Ne + (s -1 ) X x 10 11 11 2000 1800 1600 1400 1200 E(e - ) = 100 MeV E=100MeV taux de e + a l avant pour 1kW depose dans la cible e + forward 1.5 10 14 3 0 4000 1000 3000 800 2000 1000 600 90 0 400 90 0 200 0.7 10 14 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 D (μ m) D (μ m) 18/03/2005 P. Pérez & A. Rosowsky 14

Optimal Production Rates (E e+ <1 MeV) Power deposited in 1 cm 2 target = 1 kw Ne + (s -1 ) X 10 9 x 10 9 2000 1800 1600 1400 1200 1000 E(e - ) = 10 MeV E=10MeV taux de e + de moins de 1 MeV a l avant pour 1kW depose dans la cible Ee + <1 MeV 1.4 10 12 3 0 Ne + (s -1 ) X 10 9 x 10 9 10000 9000 8000 7000 6000 5000 E(e - ) = 100 MeV E=100MeV taux de e + de moins de 1 MeV a l avant pour 1kW depose dans la cible 7 10 12 Ee + <1 MeV 3 0 800 4000 600 400 0.6 10 12 3000 2000 1.5 10 12 200 90 0 90 0 1000 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 D (μ m) D (μ m) 18/03/2005 P. Pérez & A. Rosowsky 15 100μm at 3 0 /10MeV 2mm at 90 0 /100MeV

Production For 1 cm 2 of target Normalization to same number of e - generated D = 1mm Limit 1 kw / cm 2 900 800 90 0 in units of 10 12 s -1 Imax Ne + Ne + (<1MeV) 700 600 500 3 0 0.58 ma 4.6 1.1 90 0 0.25 ma 2.5 0.55 400 300 200 3 0 100 0 0 1 2 3 4 5 6 E c (MeV) 1 2 3 4 5 0.58 ma 2.3 ma for 4 cm 2 0 6 Ee+ (MeV) 18/03/2005 P. Pérez & A. Rosowsky 16

Energy versus angle Production point inside target At target exit angle Kinetic energy (GeV) 2004 Kinetic energy (GeV) 18/03/2005 P. Pérez & A. Rosowsky 17

Magnetic Bulb B target e + e + e - B B dump x target e + 18/03/2005 P. Pérez & A. Rosowsky 18

Collection Setup WALL SHIELD MAGNET H1 QUADRUPOLE TARGET DUMP MAGNET H2 HELMOLTZ GUIDING TUBE 20 cm 50 cm 40 cm 1 m count e + here 18/03/2005 P. Pérez & A. Rosowsky 19

Setup 2003 18/03/2005 P. Pérez & A. Rosowsky 20

3D view 18/03/2005 P. Pérez & A. Rosowsky 21

Setup 2004 18/03/2005 P. Pérez & A. Rosowsky 22

3D setup 2004 18/03/2005 P. Pérez & A. Rosowsky 23

Positrons y z x 18/03/2005 P. Pérez & A. Rosowsky 24

Positrons in plane H2 2004 18/03/2005 P. Pérez & A. Rosowsky 25

energy versus radius at x = 200 cm positrons Radius (cm) electrons Energy (GeV) 2004 Energy (GeV) 18/03/2005 P. Pérez & A. Rosowsky 26

Positrons radius at x = 200 cm Kinetic energy < 1 MeV All kinetic energies Radius (cm) 2004 Radius (cm) 18/03/2005 P. Pérez & A. Rosowsky 27

Transversal cuts: positrons 18/03/2005 P. Pérez & A. Rosowsky 28

e+ position in (y, z) planes Before 4-poles X = 3 cm 2004 X = 200 cm 18/03/2005 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 5 0.7 0.6 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 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 transverse radius of e + source at target level (cm) 18/03/2005 P. Pérez & A. Rosowsky 30

Version 2004 I = 2.5 ma X = 200 cm X = 320 cm e + e R yield 5 e + coll = 5 cm + rate 5 yield xe12 all 24% 5.0E-4 7.8 E <1 MeV 33% 2.4E-4 3.7 E < 600 KeV 25% 1.0E-4 1.6 I = 2.5 ma R coll = 10 cm all E <1 MeV E < 600 KeV 10 31% 36% 25% X = 200 cm e + yield 6.3E-4 2.6E-4 1.0E-4 e + rate xe12 9.8 4.1 1.6 23% 4.87E-4 7.6 32% 23% 2.37E-4 0.95E-4 5.99E-4 2.53E-4 1.02E-4 e + rate xe12 18/03/2005 P. Pérez & A. Rosowsky 31 3.7 1.5 X = 320 cm e + e yield + rate 10 xe12 29% 35% 25% 9.3 3.9 1.6

Electrons (2003) x z 10 cm 18/03/2005 P. Pérez & A. Rosowsky 32

Scattered electrons 2004 18/03/2005 P. Pérez & A. Rosowsky 33

Scattered electrons 2004 Energy deposited into SC10 from 0 to 200 cm 18/03/2005 P. Pérez & A. Rosowsky 34

Scattered electrons inside 18/03/2005 P. Pérez & A. Rosowsky 35

Scattered electrons 2004 18/03/2005 P. Pérez & A. Rosowsky 36

Scattered electrons 2004 18/03/2005 P. Pérez & A. Rosowsky 37

Scattered electrons 2004 18/03/2005 P. Pérez & A. Rosowsky 38

Energy deposited energy in % of total deposited beam energy de/dx magnet H1 HLM1 = 0.000122330341 de/dx magnet H2 HLM2 = 0.0286305789 de/dx magnet H4 HLM4 = 0.0682362914 de/dx dump SCR2 = 0.000255941792 de/dx magnet H3 HLM3 I = 1 0.0091400696 de/dx magnet H3 HLM3 I = 2 0.00750565063 de/dx magnet H3 HLM3 I = 3 0.00405035447 de/dx magnet H3 HLM3 I = 4 0.00288876216 de/dx magnet H3 HLM3 I = 5 0.00254936377 de/dx magnet H3 HLM3 I = 6 0.00162501738 de/dx magnet H3 HLM3 I = 7 0.00172283954 de/dx magnet H3 HLM3 I = 8 0.00202953094 de/dx magnet H3 HLM3 I = 9 0.000685093924 de/dx magnet H3 HLM3 I = 10 0.000578379841 de/dx magnet H3 HLM3 I = 11 0.00041745021 de/dx magnet H3 HLM3 I = 12 0.000419273681 de/dx rod H3 ROD3 I = 1 0.010669956 de/dx rod H3 ROD3 I = 4 0.00951220281 de/dx rod H3 ROD3 I = 9 0.00702352962 de/dx rod H3 ROD3 I = 12 0.00500533357 de/dx SCR4 = 0. de/dx SCR5 = 0. de/dx SCR6 = 0. de/dx SCR7 = 0.00640179683 de/dx SCR8 = 2.370119E-05 de/dx SCR9 = 7.97315661E-05 de/dx SC10 = 0.356774747 de/dx SC11 = 0.147463262 de/dx SC12 = 5.45780676E-05 de/dx SC4P = 0.00213429541 de/dx ROD2 = 0.0340836123 de/dx RDUP = 0.00375873246 de/dx LIK3 = 0.0216296595 de/dx RAIL = 0.0265459437 de/dx deflector H2 = 0.00584139721 de/dx deflector H3 = 0.00109494338 de/dx deflector DFDU = 0.000519398251 de/dx deflector SC11 = 0.00316047249 de/dx deposited in moderator = 0.000436547067 total de/dx inside target-selector cylinder = 0.996470451 2004 18/03/2005 P. Pérez & A. Rosowsky 39

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 - 18/03/2005 P. Pérez & A. Rosowsky 40

Fluxes of electrons and photons I = 2.3 ma R = 1 cm R = 2 cm R = 3 cm R = 4 cm Setup 1 5 W 140 W 450 W 1.5 kw Setup 2 10 W 45 W 80 W 110 W at exit plane Power (kw) 10 9 8 7 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 Power (kw) 10 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 Setup 1 4 Setup 2 3 2 1 0 0 0 50 100 150 200 250 300 0 50 100 150 200 250 300 X (along coils axis) (cm) X (along coils axis) (cm) 18/03/2005 P. Pérez & A. Rosowsky 41

No target No dump ( setup 2) Exit tube 18/03/2005 P. Pérez & A. Rosowsky 42

No target (2004) 18/03/2005 P. Pérez & A. Rosowsky 43

Selector field map 18/03/2005 P. Pérez & A. Rosowsky 44

electrons positrons 18/03/2005 P. Pérez & A. Rosowsky 45

Selector: electrons electrons 18/03/2005 P. Pérez & A. Rosowsky 46

Selector: positrons 0.5~0.2 positrons selected 18/03/2005 P. Pérez & A. Rosowsky 47

Separation e+ e- Target Collector e- from pairs e+ below 1 MeV Selector e- not from pairs e+ above 1 MeV e+ below 1 MeV 2 steps e+ isolation priority to e+ << 1 MeV!!! 18/03/2005 P. Pérez & A. Rosowsky 48

A very first design of a 2D expander/uniformizer F. Meot and T. Daniel, NIM, A 379 (1996) 196-205. β (m) 800. 700. (m) 600. 500. G4 inverse, expander Linux version 8.23/06 02/11/03 08.01.35 βx βy Postprocessor/Zgoubi NoDate... Z (m) vs. Y 400. 300. Z (m) 0.01 0.005 0.0 -.005 -.01 200. 100. 0.0 0.008 0.007 0.006 0.005 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 s (m) δe/ p0c =0. Table name = TWISS G4 inverse, expander Linux version 8.23/06 02/11/03 08.01.35 SIGX SIGY -.01 -.005 0.0 0.005 0.01 Y (m) 0.004 0.003 0.002 0.001 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 s (m) δe/ p0c =0. Table name = TWISS x (m) 18/03/2005 P. Pérez & A. Rosowsky 49

Expander (2) 0.02 Z (m) vs X 0.02 Y (m) vs X 0.015 0.015 0.01 0.01 0.005 0.005 0.0 0.0 -.005 -.005 -.01 -.01 -.015 -.015 0.0 0.5 1. 1.5 2. 2.5 3. X (m) 0.0 0.5 1. 1.5 2. 2.5 3. X (m) 18/03/2005 P. Pérez & A. Rosowsky 50

Expander (3) q (rad) 0.006 0.004 0.002 0.0 -.002 -.004 j (rad) 0.006 0.004 0.002 0.0 -.002 -.004 -.006 -.001 -.0005 0.0 0.0005 0.001 Z (m) -.006 -.008 -.004 0.0 0.004 0.008 Y (m) 18/03/2005 P. Pérez & A. Rosowsky 51

Optimal Production Rates (E e+ <1 MeV) What next Finalize injection scheme (F. Meot/Saclay) Finalize engineering of collection system (SACM/Saclay) Shielding scheme: depends on location Study moderation a la DELFT hot or cold before trap 18/03/2005 P. Pérez & A. Rosowsky 52

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 trap temperature Tungsten 10-4 room Neon 10-2 7K Ne moderator 1.5 ev e + 18/03/2005 P. Pérez & A. Rosowsky 53

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 18/03/2005 P. Pérez & A. Rosowsky 54

Other designs Thermal neutron capture: 113 Cd(n,) 114 Cd = 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 18/03/2005 P. Pérez & A. Rosowsky 55

IBA2204-56 / Apr 1999

Operating principle (1) D E E G IBA2204-57 / Apr 1999

Rhodotron Models - Basic Specifications TT100 TT200 TT300 Energy (MeV) 3-10 Power range at 10 MeV (kw) 1-35 Design value (kw)* 45 3-10 3-10 1-80 1-150 100 > 200 Full (cavity) diameter (m) Full (cavity) height (m) Weight (T) 1.60 (1.05) 3.00 (2.00) 3.00 (2.00) 1.75 (0.75) 2.40 (1.80) 2.40 (1.80) 2.5 11 11 MeV/pass Number of passes 0.833 12 1.0 10 1.0 10 Stand-by kw used Full beam kw used <15 <15 <15 <210 <260 <370 IBA2204-58 / Apr 1999

Our bias. Idea for e+ use since 10 ~ 20 years.. but 10 largest US Univ: how many have a source? off the shelves components No neutron safety required low maintnance : 1 engineer low running costs : < 500 kwatts 18/03/2005 P. Pérez & A. Rosowsky 59

Compact e+ factory Ne + below 1 MeV > 10 13 s -1 Ne + at 1 ev > 10 10 s -1 Beam energy/intensity : 10 MeV ~2.5 ma Interdisciplinary lab: HEP Plasma Condensed Matter SR radiation control and infrastructure 10 MeV Linac target - collector beam dump 18/03/2005 P. Pérez & A. Rosowsky 60

Engineering improvements Replace H1 and the 4-poles Use hight Tc supraconductor No field on the beam axis: stable injection New vaccum chamber with magnets outside 18/03/2005 P. Pérez & A. Rosowsky 61

Version 2004 I = 2.5 ma X = 200 cm X = 320 cm e + e R yield 5 e + coll = 5 cm + rate 5 yield xe12 all 24% 5.0E-4 7.8 E <1 MeV 33% 2.4E-4 3.7 E < 600 KeV 25% 1.0E-4 1.6 I = 2.5 ma R coll = 10 cm all E <1 MeV E < 600 KeV 10 31% 36% 25% X = 200 cm e + yield 6.3E-4 2.6E-4 1.0E-4 e + rate xe12 9.8 4.1 1.6 23% 4.87E-4 7.6 32% 23% 2.37E-4 0.95E-4 5.99E-4 2.53E-4 1.02E-4 e + rate xe12 18/03/2005 P. Pérez & A. Rosowsky 62 3.7 1.5 X = 320 cm e + e yield + rate 10 xe12 29% 35% 25% 9.3 3.9 1.6

Positron energy spectrum Same number of electrons on target E(e - ) = 10 MeV E(e - ) = 100 MeV 45000 900 Ne + 800 Ne + 40000 35000 Low energy e + escape thin target 700 600 90 0 1mm 30000 3 0 150 μm 500 25000 400 300 200 3 0 50 μm 20000 15000 10000 90 0 3 mm 100 5000 0 0 1 2 3 4 5 6 E c (MeV) E e+ (MeV) 0 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 E e+ (GeV) 10 MeV 18/03/2005 P. Pérez & A. Rosowsky 63 100 MeV