DOE REVIEW TASK C Aug. 21-22, 2006 * WORK AT SLAC Babar & ILCR. Prepost FacultyS. Dasu FacultyH. Band Senior ScientistK. Flood PostDocM. Pierini PostDoc Students

J. Hollar Graduates 8/06 C. Vuosalo Started 6/06* R. Prepost Presentation

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Task ActivitiesBaBar Physics AnalysisBaBar System Work IFR Muon System ManagementBaBar Particle ID Muon ID/Neural Net Development ILC Polarized Photocathode R&D Source Laser Development SiD Muon System KPIX ADC IC Testing

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Projected data sample growthIntegrated Luminosity [fb-1]121720Lpeak = 9x1033

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Babar AnalysesCompleted Theses

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Babar Analyses Current Analyses

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Constraints to CKM Triangle from Vtd/Vts Limits. (From Thesis of P. Tan)

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Status of the Unitarity Triangleby Utfit collaboration

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Sensitivity to New Physics in B mixing for different size data sets.DmBdEXP = CBdDmBdSM ACP(J/yK0) = sin (2(b + fBd))

extrapolation to BaBar+Bellefinal sample(~2008)CBd =1 and fBd=0 in the Standard ModelICHEP06:CBd = 1.25 0.43fBd = (-2.9 2.0)oextrapolation to 10 ab-1 ofSuperB factoryNow08Super B

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BaBar System Work - BandRPC ManagementRPC Studies and Gas ChemistryForward EndCap UpgradeRPC Operations Band and StudentsBaBar Particle ID Flood/Hollar/Band Muon Identification

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Near Term Plans2006-2007 (Analyses using 400 fb1)Complete D mixing analysisUse complete dataset through 2006 (K. Flood)Complete b s l+ l analysis including asymmetriesImprovements from NN m ID and reconstruction of several Xs final states, much like in Eichenbaum b s analysis (K. Flood)Continue Global analysis of CKM parametersAdd new results from BaBar and Belle (M. Pierini)Time dependent CP asymmetriesUpdate of B K K K analyses (M. Pierini) Update of B K 0 analysis (M. Pierini)New study of B K + analysis (M. Pierini)Rare decaysFinish B l+ l analysis (M. Pierini) Recoil technique to study difficult rare decays (C. Vuosalo)Improve the technique to study, e.g., B K and B K

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Long Term Plans2006-2008 (Analyses using 1 ab1)Exclusive B K*g & semi-inclusive b sgACP and DI measurements continue to be sensitive Semi-inclusive b s l+ l Improve ACP and forward-backward asymmetry zero-crossing pointB rg / B K*g Improve Vtd/Vts to compete with mixing measurement Measure CKM parameters in rare decaysContinue to probe for deviations from Standard ModelRecoil methodFully reconstruct one B to reduce backgroundsReduced signal statistics compensated by improved systematicsAccess to rare decays with neutrinos, Knn, Ktt Cleaner samples of inclusive decays of the other BLepton flavor violating decaysSimilar to the recoil method

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PapersEichenbaum PRL 93, 21804 (2004); PRD 72, 052004 (2005).

Ping/Dasu PRD 70, 112006 (2004); PRL 94, 011801 (2005).

Hollar Lepton Photon 05 Paper; PRD 73, 092001 (2006).

Band (IFR) NIM A552, 27 (2005); NIM A539, 155 (2005); NIM A538, 801 (2005).

Prepost Appl. Phys Lett. 85, 2640 (2004).

Pierini JHEP 0603, 080 (2006); PRD 72, 051103 (2005); PRD 71, 111102 (2005); PRL 95, 011801 (2005).

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TALKSConference Presentations 05-06

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TALKS (Continued)

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ILC Polarized SourceProposal to LC Accelerator R&D at Universities. Awards FY05 and FY06 of $34.6k/FYBudget for X-Ray Analysis, SIMS Analyses and Photoluminescence Hardware.Group expands effort to include full electron polarized source system.

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Components of Polarized Source R&DSource Laser R&DPhotocathode StructuresMeasurement of Photocathode Spin Relaxation Times: Faraday Rotation (new experiment & setup)

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Polarized Source R&D Program

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Source Laser Block DiagramWisconsin HardwarePockels Cell & Amplifier

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Wisconsin Hardware

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New SBIR with SVT AssociatesCompleted 2002 Phase 2 SBIR Study of GaAs/GaAsP Superlattice.Submitted new Phase 1 SBIR for Study of GaAs/InGaP Superlattice. Approved 2005.Highly Polarized Photocathodes Via Minimization of Spin RelaxationInGaP has lower spin relaxation than GaAsP: expect reduced depolarization. Also expect Quantum Efficiency Enhancement.

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SVT SBIR Phase I StructuresGaAs/InGaP strained superlattice

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Three structures with 1.25% lattice mismatchEc (eV)Ev (eV)Strained wellsStrained wellsStrained barriersHHLH

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Structures Strained wells1) 5 nm GaAs cap Be: 1x10^192) 4 nm In(0.32)Ga(0.68)P Be: 1x10^173) 4 nm GaAs Be: 1x10^17

repeat 2) and 3) 12 times

4) 2.5 um In(0.32)Ga(0.68)P Be: 5x10^185) 2.5 um In(x)Ga(1-x)P x=0.48 -> 0.32 Be: 5x10^186) In(0.48)Ga(0.52)P buffer lattice-matched to GaAs7) GaAs substrate

Strained Barriers1) 5 nm GaAs cap Be: 1x10^192) 4 nm In(0.65)Ga(0.35)P Be: 1x10^173) 4 nm GaAs Be: 1x10^17

repeat 2) and 3) 12 times

4) 1 um Al(0.3)Ga(0.7)As Be: 5x10^185) GaAs buffer6) GaAs substrate

= 767 nmEhh-lh = 109 meV= 832 nmEhh-lh = 62 meV

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SVT SBIR Phase-I WafersI) Strained wells SVT-3039

1) 5 nm GaAs cap Be: 1x10^192) 4 nm In(0.31)Ga(0.69)P Be: 1x10^173) 4 nm GaAs Be: 1x10^17

repeat 2) and 3) 12 times

4) 2.5 um In(0.31)Ga(0.69)P Be: 5x10^185) 2.5 um In(x)Ga(1-x)P x=0.48 -> 0.31 Be: 5x10^186) In(0.48)Ga(0.52)P buffer lattice-matched to GaAs7) GaAs substrate

II) Strained barrier SVT-3031

1) 5 nm GaAs cap Be: 1x10^192) 4 nm In(0.65)Ga(0.35)P Be: 1x10^173) 1.5 nm GaAs Be: 1x10^17

repeat 2) and 3) 18 times

4) 1 um Al(0.3)Ga(0.7)As Be: 5x10^185) GaAs buffer6) GaAs substrate

SVT-30171.5 nm In(0.65)Ga(0.35)P4 nm GaAsThree wafers have been grown.

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Polarization and QESVT-3039First MeasurementsWill re-measure all three samples.Will X-ray all three samples.

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Faraday Effect Rotation to Measure Spin Relaxation TimesPrepare Pump/Probe Laser Pulses with Variable Probe Delay Time.Pump with Circularly Polarized Light to Create Polarized Electrons in the Conduction Band.Probe with Linearly Polarized Light Laser Pulse at Time t wrt Pump. Measure the Rotation Angle of the Linear Polarization as a Function of time t. The Rotation Angle is Proportional to the Polarization. A Series of Measurements will give P(t) and thus the Relaxation t.Requires a laser with femtosecond pulses to be able to measure picosecond values of t.

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Status of Faraday Rotation ExperimentFemtosec laser to be delivered to Wisconsin on Sep. 1. The laser will be tested at Wisconsin.480 V power and AC crash buttons installed. Argon Ion laser can be operated.Fieguth, Bower, and Schmerge came to the lab on Aug. 10 to go over the SOP and laser safety issues.Interlock switches need to be installed.New goggles to be purchased.SOP to be revised.Shooting for a laser safety approval in mid September.

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Faraday Rotation Laser

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