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Positron Target R&D at KEKPlan and Status

AD&I Meeting 2009/8/27 KEK

Hybrid Target Test at KEKB Linac

Liquid Lead Target Test at ATF Linac

Window Test at KEKB Beam Abort

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Hibrid Target TEST at KEKB LINAC

1 To Demonstrate • positron yield with the hybrid system• heat reduction by hybrid target

2. Detail investigation toward the positron source• momentum distribution,• ( angular distribution of e+ )

w/ a real beam (angular divergence, alignment) and crystal (mosicity),,,

JFY2009

JFY2010~

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experimental site KEKB LINAC

e+ source

Switch yard

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Site Set upLooking up from Down stream

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Status

Major Equipments Sweeping Magnet Analyzer magnet, detectors, beam dumps have installed at the end of KEKB LINAC

First experiment expected in September

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A design for the ILC (Chehab et.al)

• INCIDENT BEAM: 10 GeV• TARGETS:

• CRYSTAL: a 1 mm thick W crystal <111>orientation• AMORPHOUS: an 8 mm thick amorphous target

• CAPTURE SYSTEM: AMD with decreasing field from 6 to 0.5 Tesla on 50 cms Accelerating field is 18 MeV/m, peak [SW]

• Accepted yield: 1.5 e+/e- (2.5 mm) • PEDD/bunch:

• assuming an incident e- bunch of 2. 1010 e-2.5mm crystal amorphous 0.058 J/g/bunch 0.33 J/g/bunch

Amorphous target may survive with 300 Hz design

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Beam IntensityDesign for ILC 300Hz

KEKB Linac

Beam Energy 10GeV 8GeV

Rms beam size 2.5mm Controllable

> 0.4mm

Bunch charge 3.2nC < 2nC

# of bunches in 300ns

132 1 (rep rate 25Hz)

Bunch intensity is sufficient, but energy in 300ns (shockwave time scale) is far below the ILC design.

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Liquid lead target test

at ATF Linac End

Liquid lead 300℃

4.5m 10.3m 2.0m

We kek decided to do the beam experiment with BINPprototype liquid lead target.

Bend

QQ

Target

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function tuning range : 0.1m to 10mBunch structure : 1 to 20 bunches/trainBunch charge : 0.5 to 2.0 x 1010 electrons/bunchBeam energy : 1.3GeVRepetition rate : 0.7 to 6.25HzUsual normalized emittance : less than 10mmmradBeam size : 0.2 to 2.0mm

Energy density on target0.006 to 48 x 1010 GeV/mm2

Power deposit on target0.004 to 300 x 1010 GeV/mm2 sAcceptable beam rep. rate?

ATF Linac Beam Parameters

1004/20/23 10

(0.017-50 x1012 GeV/mm, 40kW) in the case of Undulator scheme (0.02-60 x1012 GeV/mm, 290kW) in the case of 1msec ILC like beam, (2 x1012 GeV/mm2, 2 kW) in the case of new scheme. (0.7 x1012 GeV/mm2, 30kW) in the case of X-band LC with three targetsNLC and JLC

Need the data for Titanium Alloy.

[???]

Logachev Plot under consideration

ATF Linac BeamTest Area

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Scheme of the prototype of liquid lead positron production target.

Driving motor

Rotating vacuum feedthrough

Vacuum pump

Vacuum tank of the system

Cog-wheel pump

Liquid lead transport tubes

Target head

Window thickness 4mmBN disks for windowsDiameter 12mm

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Systematic experimental studies on Liquid 90%Pb+10%Sn target system with BN window will start from late 2009. (Maybe, end of this year.)We are still discussing what kind of measurements are necessary for ILC target system and detail schedule.

To learn the operation of this liquid target is importantfor the evaluation of the reliability and the maintainabilityand we can propose very reliable target system for ILCe+ source with a lot of simulation and some proofs of experimental results.

Tentative Schedule and SummarySchedule : transport of the proto type will be end of Oct..Stand alone self testing will be in Nov..Installation will be in Dec.. This schedule is not fixed.

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Liq. Pb Window Test at KEB► By injecting the KEKB stored beam

into a test target, any damages on the ILC e+ production target can be reproduced.

► KEKB mode : just inject KEKB stored beam.

► ILC mode : modify the abort kicker and bunch fill pattern to reproduce more realistic ILC drive beam.

Stored beam and dump► KEKB-HER: 8GeV, 10nC, 1300

bunches (1300mA)

► The beam is deflected by the abort kicker as shown when it is dumped.

► Because of “Step size” variation, the energy density is varied from 1810 to 13700 J/mm2.

Dump pattern

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KEKB Beam Dump setup► It is a test for isolation window

material for liquid Pb target system.

► Space is very limited for KEKB BD.

► Solid Radiator (Solid Pb) is placed before BN plate, as a test material.

► The sample is fixed with support rod, which also acts as cooling channel.

► Thermo-coupler, acoustic sensor for monitor.

► Final investigation for damage is made by optical and laser microscopy.

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Beam Condition

• 10nC, ~1500 bunches, 10s

• Bunch-by-bunch impossible

• Unable to change beam size(~1mm rms?)

• Swept by kicker (protect extraction window)

• Moves 7 ~ 4m/bunch on target (0.9mm ~ 6mm over 132 bunches)

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Schedule• KEKB operation Oct-Dec (~2 months)

(Must get window material from BINP)• ~3yrs long shutdown from January for SuperKE

KB upgrade. Experiment impossible.• Use the beginning of 8hr maintenance time ever

y other week.• A pilot shot (maybe single bunch) needed for ali

gnment check• Have to wait ~1hr? for radiation cooling after eve

ry shot. • General agreement by KEKB team. Detail must

still be worked out.

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Beam Intensity for LPb TargetRDR withLPb target

300HzDesign

ATF LinacEnd

KEKB Abort

Beam Energy ~30MeV(photon)

3.5GeV (e) 1.3GeV (e) 8GeV (e)

Bunchpopulation

~2x10̂ 12 3.7x10̂ 10 < 2x10̂ 10 6x10̂ 10

Bunch energy 10J (photon) 21J (e) 6J (e) 80J (e)Rms beam size ~1mm ? ~2mm ? > 0.2mm

(tunable)~1mm (fixed)

incident energyin 300ns

10J 2700J(132bunches)

125J(20bunches)

3600J(45bunches)

incident energyin 3ms

25kJ in 1ms 2.7kJ 0.125kJ 120kJ(1500bunches,in 10mic.sec,2D sweep)

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backup

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KEKB mode : reproduces only the energy density.

195(15) 270-1370 2 635

390(30) 540-4100 1 1270

1300(100) 1810-13700 0.7 1810

Total Current (mA)

Energy density (J/mm2)

ILC pulse length (ms)

Energy density (J/mm2)

* Assume 1mm2 spot size.

ILC Mode : reproduce both energy flux and density.

► Turning off the vertical kicker.

► Fill 1 or 2 bunches only at zero-cross.

► These bunches hit a same spot every 1430ns .

80n J

No sw

eep in vertical

SLAC ILC ILC (0.7) ILC (1) ILC(2)

Energy flux (J/us) large 52.92 45.69 65.27 130.54

320 1270 392 560 1120

duration (us) 0 24 8.58 8.58 8.58

7.0 x 7 10.0 x 7 10.0x14

Energy density(J/mm2)

Fill pattern (nC x Nb)

2004/20/23 20

20 Cog-wheel pump test bench is in continuous run (20000 h) with liquid lead jet. 90% Pb, 10% Sn alloy at 300ºC.

Liquid lead jet in vacuum