PEP-II test chambers installation SEY GROOVE 1 GROOVE 2 FLAT 1 FLAT 2 COLLECTORS ENERGY ANALYZER THERMOCOUPLES GROOVE CHAMBERS EXPERIMENT SEY TEST STATION

SEY test station in PEP-II LER 0o position 45o position

Fin/Flat TiN chambers in PEP-II LER Flat chamber Fin chamber

Secondary Electron Yield Measurements at SLAC

SEY test chamber 19 March 2007

Grooved chambers

Collector signals vs PEP-II LER current Stainless steel chamber Electron integrated energy distribution Stainless steel chamber Collector signal vs retarding grid field (10V = - 500V) PEP-II LER current still raising (2.7A  4A)

Compare vacuum chamber e- currents Measured e- current in grooved and TiN flat chambers << StSt chamber. PEP-II LER current still raising (2.7A  4A)

Solenoid on and conditioning effect 14jan 17mar 18jan 19jan External solenoid on, grooved/flat chambers (10A  Bz=20 Gauss) Electron and photon conditioning in time on stainless steel chamber 3 days ROD starting next Monday, 1st sample transferring to laboratory for SEY and surface measurements after prolonged e- and ph dose.

Ready for INSTALLATION Coating of extruded Al chambers Projects ONGOING TESTS AT SLAC: TEST in LOCATION Ready for INSTALLATION Status SEY TESTS STRAIGHT PEP-II LER PR12 November 2006 Ready FINS RECTANG. Coating of extruded Al chambers ONGOING PROJECTS: CLEARING ELECTRODES BEND PEP-II LER PR12 FY07-FY08 Design FINS TRIANG.

Layout installation – in PEP-II f 3.5” f 1.73” Proposed reduction in chamber diameter Chamber cross section 22” ~25” 59” (D-BOX) (D-BOX) BEND BEND BEND BEND tapered chamber 1 spool chamber Grooved chamber(?!) Clearing electrode chamber tapered chamber 2 D-BOX=diagnostic box, electron detection centered on BEND and 13.5” long

Test Chamber Assembly, 1.5M Long (59.00”) Vacuum Tube, 3.75 OD x 3.51 ID 3.375” CFF, Rotatable Vacuum Tube, 4.00 OD x 3.50 ID Collector Port Flange 3.375” CFF, Non-Rotatable Tube, 2.00” OD x 1.73” ID Flange to Flange Length = 59.00” 1.33” CFF access port Feedthrough, Ceramtec #1084-01-W Mounted to 1.33” CFF

Test Chamber with Electrode Electrode, Copper 0.063” x ~1.0” x 50.0” (49.606” between feedthrough centers) Clearance between Electrode and chamber Varies between .070” and .080”

LTOT Rpipe 1 t h3 h1 h2 LTAP Dimensions: LTOT630 mm LTAP115mm Rpipe=44 mm =60 deg h1,h3,h3=5 mm t=2 mm 2nd Geometry: 1 Ports 50 Ohm 1st Geometry: 2 Ports 50 Ohm LTOT Rpipe 1 David Alesini, Frascati, Feb 2007 t h3 h1 First discontinuity LTAP h2

HFSS Results on Copper electrode stainless steel chamber D.Alesini Frascati A. Krasnykh, SLAC, Mar 2007 Longitudinal Impedance: power deposited to electrode ~10W with PEP-II beam, and ~2W for ILC DR beam.

Triangular groove chamber – (see Lanfa)

Single-bunch instability preliminary studies ongoing. Cmad simulation code status Tracking the beam in a MAD lattice for ILC DR, parallel code, interaction with cloud at each element in the ring and with different cloud distribution, single-bunch instability studies, threshold for SEY, dynamic aperture tune shift … CMAD [M. P.] Single-bunch instability preliminary studies ongoing. Electron cloud build-up (SEY, vacuum chamber, etc.) to be added. ns=0.067 e- density 1e10 e/m3 macrop=100000 ILC DR MAD deck to track beam with an electron cloud at each element of the ILC DR. First results: 2 synchrotron oscillation periods (9min * 320 CPUs / turn) CMAD tracking, ILC DR beam at extraction, with average cloud density 1e10 e/m3 (below threshold). Bottleneck => in ILC DR, beam aspect ratio reaches sx/sy=200, demanding Particle in Cell grid ratios num-gridx >> num-gridy, to correctly simulate Electric field.

Motivations and solutions summary e-cloud observed at SPS and PS (CERN), PEP-II, KEKB, Dafne, CESR concern for: ILC DR & CLIC, LHC, LHC+, SPS with PS2, KEKB, Dafne best approach: avoid e-cloud build up technological solutions: - NEG non-evaporable getter coating (SPS, LHC 6km warm sections, RHIC, PEP-II, KEKB) - TiN coating (Daphne wigglers, PEP-II, KEKB) - grooves (PEP-II, SPS, CESR) - “conventional” clearing electrodes (PEP-II, KEKB, DAFNE(?!), SPS) - novel enamel clearing electrode (clearing electrode based on double layer of enamel coating, SPS) slotted surface shielding beam fields (CERN) air baking techniques (SPS, SLAC)

Global R&D program Ongoing: At KEKB Secondary electron yield (SEY) in situ, ante-chamber and thin films coatings TiN and NEG. Planning: clearing electrodes tests planned at KEKB in a wiggler magnet section At SLAC Conditioning and SEY of TiN and NEG samples in PEP-II beam line, groove chambers. Planning: clearing electrodes and triangular grooves in bends with parameters close to ILC DR. Planned: At CERN: concern for the SPS and PS as LHC pre/injectors. Planning: several mitigation techniques are under evaluation for the SPS and PS: increase chromaticity, scrubbing runs, smaller radii chambers, NEG coating, grooved surfaces, air baking and slots. Clearing electrodes on enamel substrate. In Daphne, limitation on maximum positron current. Suspected electron cloud. Al chambers: Planning: TiN film coatings in the wiggler Al chambers. (excluded by now clearing electrodes) Cornell CesrTA: > FY08, Electron cloud in wiggler sections with ILC DR parameters. Ultra-low emittancies. Fast Beam Ion instability.

Thanks ! To the contributors to this presentation M. Palmer (Cornell), S. De Santis (LBNL) F. Willeke (DESY), K. Suetsugu (KEK), K. Bane, P. Raimondi, L. Wang (SLAC), F. Zimmermann (CERN) and to DR collaborators D. Arnett, G. Collet, R. Kirby, N. Kurita, B. Mckee, M. Morrison, P. Raimondi, T. Raubenheimer, J. Seeman, L. Wang, G. Stupakov (SLAC), D. Rubin, D. Rice, L. Schachter, J. Codner, E. Tanke, J. Crittenden (Cornell), J. Gao (HIPEP), A. Markovic et al. (Rostock Univ.), M. Zisman, S. De Santis, C. Celata, M. Furman, J.L. Vay (LBNL), K. Ohmi, Y. Suetsugu (KEK), F. Willeke, R. Wanzenberg (DESY), J.M. Laurent, A. Rossi, E. Benedetto, F. Zimmermann, G. Rumolo, J.M. Jimenez, J-P. Delahaye (CERN), A. Wolski (Cockroft Uniiv.), B. Macek (LANL), C. Vaccarezza, S. Guiducci, R. Cimino (Frascati), et many other colleagues…

International Linear Collider R&D on electron cloud (SLAC) M. Pivi, T. Raubenheimer, J. Seeman, T. Markiewicz, R. Kirby, F. King, B. McKee, M. Munro, D. Hoffman, G. Collet, L. Wang, A. Krasnykh, D. Arnett, (SLAC) M. Venturini, M. Furman, D. Plate (LBNL), D. Alesini (LNF Frascati) R. Macek (LANL) 19 March 2007