1 Positron Target R&D at KEK Plan 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

2 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~

3 experimental site KEKB LINAC e+ source Switch yard

4 Site Set up Looking up from Down stream

5 Status Major Equipments Sweeping Magnet Analyzer magnet, detectors, beam dumps have installed at the end of KEKB LINAC First experiment expected in September

6 A design for the ILC (Chehab et.al) INCIDENT BEAM: 10 GeV TARGETS: CRYSTAL: a 1 mm thick W crystal 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 e-    2.5mm crystal amorphous J/g/bunch 0.33 J/g/bunch Amorphous target may survive with 300 Hz design

7 Beam Intensity Design for ILC 300Hz KEKB Linac Beam Energy10GeV8GeV Rms beam size2.5mmControllable > 0.4mm Bunch charge3.2nC< 2nC # of bunches in 300ns 1321 (rep rate 25Hz) Bunch intensity is sufficient, but energy in 300ns (shockwave time scale) is far below the ILC design.

8 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 BINP prototype liquid lead target. Bend QQ Target

9  function tuning range : 0.1m to 10m Bunch structure : 1 to 20 bunches/train Bunch charge : 0.5 to 2.0 x electrons/bunch Beam energy : 1.3GeV Repetition rate : 0.7 to 6.25Hz Usual normalized emittance : less than 10  mmmrad Beam size : 0.2 to 2.0mm Energy density on target to 48 x GeV/mm 2 Power deposit on target to 300 x GeV/mm 2 s Acceptable beam rep. rate? ATF Linac Beam Parameters

/10/2610 ( x10 12 GeV/mm, 40kW) in the case of Undulator scheme ( x10 12 GeV/mm, 290kW) in the case of 1msec ILC like beam, (2 x10 12 GeV/mm 2, 2 kW) in the case of new scheme. (0.7 x10 12 GeV/mm 2, 30kW) in the case of X-band LC with three targets NLC and JLC Need the data for Titanium Alloy. [???] Logachev Plot under consideration ATF Linac Beam Test Area

11 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 4mm BN disks for windows Diameter 12mm

12 Systematic experimental studies on Liquid 90%Pb+ 10%Sn target system with BN window will start from late (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 important for the evaluation of the reliability and the maintainability and we can propose very reliable target system for ILC e+ source with a lot of simulation and some proofs of experimental results. Tentative Schedule and Summary Schedule : 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.

13 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 J/mm2. Dump pattern

14 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.

15 Beam Condition 10nC, ~1500 bunches, 10  s Bunch-by-bunch impossible Unable to change beam size (~1mm rms?) Swept by kicker (protect extraction window) Moves 7  ~ 4  m/bunch on target (0.9mm ~ 6mm over 132 bunches)

16 Schedule KEKB operation Oct-Dec (~2 months) (Must get window material from BINP) ~3yrs long shutdown from January for SuperKEKB upgrade. Experiment impossible. Use the beginning of 8hr maintenance time every other week. A pilot shot (maybe single bunch) needed for alignment check Have to wait ~1hr? for radiation cooling after every shot. General agreement by KEKB team. Detail must still be worked out.

17 Beam Intensity for LPb Target

18 backup

19 KEKB mode : reproduces only the energy density. * Assume 1mm 2 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 sweep in vertical

/10/2620 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