Chicago CP Group: KTeV and Braidwood Ed Blucher

Chicago CP Group: KTeV and Braidwood Ed Blucher Overview of group Status of KTeV analysis Braidwood Neutrino Experiment 15 January 2005 University of Chicago NSF Site Visit Current group members (KTeV + Braidwood): Faculty: Ed Blucher Senior research associate: Rick Kessler* (25% for 2005, 0% after) Postdoc: Matt Worcester, ongoing search Grad students: Erin Abouzaid, Elizabeth Worcester* Undergraduate students: Abby Kaboth, Jennifer Seger, David Underwood Recent departures: Sasha Glazov (postdoc); now at DESY Val Prasad (Blucher student): now at Yale

Colin Bown (Blucher/Winstein student): now at UT Austin Jim Graham (Blucher student): now at Catalyst * only KTeV + Kelby Anderson, Jim Pilcher on Braidwood The KTeV Experiment E832: / to 10-4 E799: rare KLdecays to 10-11 (data taking:1996-2000) Charged particle momentum resolution < 1% for p>8 GeV/c; momentum scale known to 0.01% from K. CsI energy resolution < 1% for E > 3 GeV; energy scale known to 0.1% from Ke. Chicago NSF: CsI calorimeter, trigger, online and offline software Chicago group physics analyses:

+ neutral K parameters (m, S, +, 00+) (Elizabeth Worcester dissertation) |Vus|: KL branching fractions, semileptonic form factors, radiative semileptonic decays 0e+e branching fraction (Erin Abouzaid dissertation) Semileptonic charge asymmetry mass K* mass KL+0 and KL000 form factors : Indirect vs. Direct CP Violation: (Blucher,Glazov,Graham,Kessler,Prasad,Worcester) KL~ Kodd + Keven Direct in decay process

Indirect from asymmetric 0 K 0 K mixing To distinguish between direct and indirect CP violation, compare KL,S,: 1 K L / K s Re /

1 0 0 0 0 6 K L / K s / 0 direct CP violation K 0 K 0 KTeV Result: Re() = (20.7 1.5(stat) 2.4(syst)) 10-4 = (20.7 2.8) 10-4 World average: Re() = (16.6 6) (confidence level = 10%)

A. Alavi-Harati et al (KTeV), Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters in the Neutral Kaon System, Phys. Rev. D 67, 012005 (2003). KL - KS Interference Downstream of Regenerator KTeV Results: m (5261 15) 106 s 1 S (89.65 0.07) 10 12 s SW 0.61 0.62 (stat) 1.01 (syst) 00 0.39 0.22 (stat) 0.45 (syst) History of KS Lifetime and m Measurements Current Analysis 96+97 1999 96-99

Vacuum beam (KL) Reg. Beam ("KS") 00 + 00 (106) (106) (106) (106) 11.2 3.4 19.4 5.6 14.9 3.7 25.8 6.1 26.1 7.1 45.2 11.7

)stat (10-4) 1.5 1.4 1.0 Improvement in systematics needed to take advantage of increase in statistics. Better treatment of nearby and overlapping clusters: E scale, E nonlinearity Better modeling of fringe field: calorimeter calibration, E nonlinearity Improved drift chamber alignment: calorimeter calibration, E nonlinearity Improved simulation of delta rays: pt distribution, neutral background estimate Better drift chamber performance (99) and track reconstruction: mass resolution improved by ~10%. Full treatment of photon angles in simulation and reconstruction: E scale, E

nonlinearity All improvements implemented; detailed data-MC comparisons underway. K00 Analysis: Seed block energy distribution Data/MC Ratio Data MC Clusters / 0.5 GeV K+ Analysis: Full data sample 2002 Analysis (published) 2005

Analysis Bench Tests with prototype drift chamber (DC) and full KTeV electronics to study pathologies observed in DC resolution. DC wire A New Determination of |Vus| (Blucher, Glazov, Kessler) Motivation: For first row, PDG quotes 2.2 deviation from unitarity: 2 2 1 Vud Vus Vub 2

0.0043 0.0019 (PDG 2002) Recent K+ measurement from BNL E865 consistent with unitarity. Interesting to revisit KL measurements (PDG fit values based on averages of many old experiments with large errors) Determination of |Vus| in Semileptonic KL Decays KTeV measures form factors needed to calculate phase space integrals KTeV measures B(KLe) and B(KL) K 3

GF2 M K5 S EW (1 K ) Vus 3 192 Rad. Corrections (theory) 2 2 f (0) I K Form factor

at t=0 (theory) To determine the semileptonic widths, we measure the following 5 ratios: K 3 / Ke3 ( K L ) / ( K L e ) 0 / Ke 3 ( K L 0 ) / ( K L e ) 000 / Ke 3 ( K L 0 0 0 ) / ( K L e ) / Ke3 ( K L ) / ( K L e ) 00 / 000 ( K L 0 0 ) / ( K L 0 0 0 ) These six decay modes account for 99.93% of KL decays, so ratios may be combined to determine branching fractions. E.g., BKe3 K 3 000 1 Ke3 Ke 3

0.9993 0 00 000 Ke 3 Ke 3 000 Ke 3 Features of Branching Fraction Analysis Each ratio measured in statistically independent data sample collected with a single trigger (samples sizes are 105 to 106 per decay mode) Each ratio measured in two data samples: high intensity (same data used for analysis) low intensity (no regenerator and 10 lower intensity) Result for each ratio based on sample with lower total uncertainty Monte Carlo simulation is used to correct for acceptance difference between pair of modes Simulation includes inner bremsstrahlung contributions for all decay modes with charged particles, so branching fractions include radiated photons. For KL, we do not use muon system. For KL, we do not reconstruct the decay.

Neutral Decay Modes K L 0 0 and K L 0 0 0 4 or 6 photon-like clusters are paired to reconstruct two or three neutral pions consistent with a single decay vertex. (Analysis almost identical to analysis.) Comparison of data and Monte Carlo kaon energy distributions Monte Carlo spectrum was tuned using KL+ events For partially reconstructed modes, high energy solution

is plotted Data MC Comparison for Radiative Photon Candidates Ke3() and K3(): KLOR written by T. Andre. Includes virtual and real photons. K(): PHOTOS K(): KTeV generator includes IB, but ignores direct emission. Radiation changes Ke3 acceptance by 3%; effect on other modes is < 0.5%. Measured Partial Width Ratios Modes Partial Width Ratio

K3 / Ke3 0.66400.00140.0022 000 / Ke3 0.47820.00140.0053 0 / Ke3 0.30780.00050.0017 / Ke3 (4.8560.0170.023)1 03 00 / 000 (4.4460.0160.019)1 03 Comparison of KTeV and PDG Branching Fractions

Determination of |+| Using B(KL) 2 L L ( K L ) S B B 0 0 1 6 Re( / ) ( K S ) L 1 BS KTeV: 2.228 0.005KTeV 0.009 EXT 10 3 KL-KS Interference Semileptonic Form Factor Measurements

(to determine IK integrals) K 3 2 F 5 K 3 G M S EW (1 K )C 2 Vus 192 2 f 2 (0) I K IK depends on the two independent semileptonic FFs:

We use the following parametrization for f+ and f0: t 1 t2 f (t ) f (0) 1 2 4 M 2 M t f 0 (t ) f (0) 1 0 2 , M where t ( PK P ) 2 ( P P ) 2 Form Factor Results Paramete Value () r +

20.64 1.75 + 3.20 0.69 13.72 1.31 0 Semileptonic Form Factors: 0 5 more precise than PDG Summary of Vus Changes from KTeV Measurements K 3 GF2 M K5

S EW (1 K ) Vus 3 192 2 2 f (0) I K Compared to PDG: Ke3 increases by 5% K3 doesnt change Ie decreases by 1.7% I decreases by 4.2%

(both include -1% shift from +) |Vus| Results For KLe: |Vus| = 0.2253 0.0023 For KL: |Vus| = 0.2250 0.0023 Averaging these results (accounting for correlations): |Vus| = 0.2252 0.0008KTeV 0.0021ext KTeV error: branching fractions, form factors Ext error: f+(0), KL lifetime, radiative corrections 2 2 1 Vud Vus Vub 2

0.0018 0.0019 Comparison with Unitarity A 5 sigma difference! theory Vus Publications T. Alexopoulos et al (KTeV), A Determination of the CKM Parameter |V us|, Phys. Rev. Lett. 93, 181802 (2004). T. Alexopoulos et al (KTeV), Measurements of K L Branching Fractions and the CP Violation Parameter |+|, Phys. Rev. D 70, 092006 (2004). T. Alexopoulos et al (KTeV), Measurements of Semileptonic K L Decay Form Factors, Phys. Rev. D 70, 092006 (2004). T. Alexopoulos et al (KTeV), Measurements of the Branching Fractions and Decay Distributions for KL and KLe, Phys. Rev. D 71, 012001 (2005). + Chicago Sun Times, Science Blog, Newswise, ScienceDaily, etc. 0 T. C. Andre, Radiative Corrections in K 3 Decays, hep-ph/0406006,

submitted to Eur. Phys. J. C. Neutrino Oscillations During last few years, oscillations among different flavors of neutrinos have been established; physics beyond the S.M. Mass eigenstates and flavor eigenstates are not the same (similar to quarks): flavor eigenstates MNSP matrix mass eigenstates e U e1 U e 2 U e3 1 U 1 U 2 U 3 2 U U U

2 3 3 1 Raises many interesting questions including possibility of CP violation in neutrino oscillations. CP violation in neutrino sector could be responsible for the matter-antimatter asymmetry. What do we know? U e1 U e 2 U e3 Big U U 1 U 2 U 3 Big U 1 U 2 U 3 Big cos 12 sin 12 0

sin 12 cos 12 0 12 ~ 30 Big Big Big Small ? Big Big 0 cos 13 0 0 1 eiCP sin 13

0 e iCP sin 13 1 0 1 0 0 cos 23 0 cos 13 0 sin 23 sin2 213 < 0.2 at 90% CL What is e component of 3 mass eigenstate? normal inverted 0

sin 23 cos 23 23 ~ 45 Key questions What is value of 13? What is mass hierarchy? Do neutrino oscillations violate CP symmetry?2 2 2 m12 m13 m23 P( e ) P( e ) 16s c s c s c sin sin Lsin L sin

L 4 E 4 E 4 E 2 12 12 13 13 23 23 Why are quark and neutrino mixing matrices so different? U MNSP Big ~ Big Big Big Big Big Small ? Big

Big vs. VCKM 1 ~ Small Small Small 1 Small Small Small 1 Value of 3 central to these questions; it sets the scale for experiments needed to resolve mass hierarchy and search

for CP violation. DNP, DPF, DAP, DPB Joint Neutrino Study on the Future of Neutrino Physics (2004) Recommendation 2 (of 3): We recommend, as a high priority, a comprehensive U.S. program to complete our understanding of neutrino mixing, to determine the character of the neutrino mass spectrum, and to search for CP violation among neutrinos. This program should have the following components: An expeditiously deployed multi-detector reactor experiment with sensitivity to e disappearance down to sin22 = 0.01, an order of magnitude below present limits. A timely accelerator experiment with comparable sin22 = 0.01 sensitivity and sensitivity to the mass hierarchy through matter effects. A proton driver in the megawatt class or above and neutrino superbeam with an appropriate very large detector capable of observing CP violation and measuring the neutrino mass-squared differences and mixing parameters with high precision. (G. Barenboim and E. Blucher, co-leaders of Reactor Working Group) Methods to measure sin2213 Accelerators: Appearance (e)

m132 L P ( e ) sin 23 sin 213 sin not small terms ( CP , sign( m132 )) 4E 2 2 2 Use fairly pure, accelerator produced beam with a detector a long distance from the source and look for the appearance of e events T2K: = 0.7 GeV, L = 295 km NOA: = 2.3 GeV, L = 810 km Reactors: Disappearance (ee) m132 L P( e e ) 1 sin 213 sin very small terms 4E 2

2 Use reactors as a source of e (~3.5 MeV) with a detector 1-2 kms away and look for non-1/r2 behavior of the e rate Reactor experiments provide the only clean measurement of sin 22: no matter effects, no CP violation, almost no correlation with other parameters. (In combination with accelerator experiments, can resolve 23 degeneracy.) Reactor and accelerator sensitivities to sin22 90% CL exluded regions with no osc.signal CP=0, m2 = 2.510-3 eV2 (3 yr reactor, 5 yr Nova) 90% CL allowed regions with osc.signal sin2213 = 0.05, CP=0, m2 = 2.510-3 eV2 (3 yr reactor, 5 yr T2K)

2 2 matm L 2 2 msolar L P( e e ) 1 sin 213 sin sin 212 sin 4E 4E Past reactor measurements: How to improve on previous reactor 2 2 matm msolar experiments? (Chooz limit: 2 2

sin22< 0.15 for m2=2.5103 eV2) Add an identical near detector Eliminate dependence on reactor flux; only relative acceptance of detectors needed Optimize baseline (1500 m) Larger detectors (5 ton 50 tons) Reduce backgrounds (Go deeper 100m 150 to 300m) ~200 m ~1300 m The Braidwood Experiment Features of Braidwood site: 23.6 GW reactors 7.17 GW maximum power Flat: flexibility, equal overburden at near and far sites, surface

transportation of detectors Favorable geology (dolomitic limestone): good for excavation, low radioactivity (order of magnitude lower U, Th than granite) Braidwood Collaboration Argonne Nat. Lab.: M. Goodman, V. Guarino, L. Price, D. Reyna Brookhaven Nat. Lab.: R. Hahn, M. Yeh, A Garnov, Z. Chang, C. Musikas U. of Chicago: E. Abouzaid, K. Anderson, E. Blucher,* M. Hurowitz, A. Kaboth, D. McKeen, E. Pod, J. Pilcher, J. Seger, M. Worcester Columbia: J. Conrad, Z. Djurcic, J. Link, K. McConnel, M. Shaevitz,* G. Zeller Fermilab: L. Bartoszek, D. Finley, H. Jostlein, C. Laughton, R. Stefanski Kansas State: T. Bolton, C. Borjas, J. Foster, G. Horton-Smith, N. Kinzie, J. Kondikas, D. Onoprienko, N. Stanton, D. Thompson U. of Michigan: B. Roe MIT: P. Fisher, R. Cowan, L. Osborne, G. Sciolla, S. Sekula, F. Taylor, T. Walker, R. Yamamoto Oxford: G. Barr, S. Biller, N. Jelley, G. Orebi-Gann, S. Peeters, N. Tagg U. of Pittsburgh: D. Dhar, N. Madison, D. Naples, V. Paolone, C. Pankow St. Marys University: P. Nienaber Sussex: L. Harris U. of Texas: A. Anthony, M. Huang, J. Jerz, J. Klein, A. Rahman, S. Seibert

U. of Washington: J. Formaggio spokesperson Braidwood Baseline Design Goals: Flexibility, redundancy, cross checks 4 identical 65 ton fiducial mass detectors; 2 at near site, 2 at far site Two zone detectors: inner zone with Gd-loaded LS and r=2.6 m; outer zone with mineral oil and r=3.5 m. Movable detectors with surface transport for crosscalibration; vertical shaft access to detector halls Oscillation measurements using both rate and energy spectrum Full detector construction above ground Near and far detectors at same depth of 450 mwe with flat overburden; deep near detector will allow measurement of sin2W. Detectors and analysis strategy designed to minimize relative acceptance differences Shielding

Central zone with Gd-loaded scintillator surrounded by buffer regions; fiducial mass determined by volume of Gd-loaded scintillator Neutrino detection by e p e n, n Gd 8MeV of s; ~ 30 sec 6 meters To reduce backgrounds: depth + active and passive shielding Events selected based on coincidence of e+ signal (Evis>0.5 MeV) and s released from n+Gd capture (Evis>6 MeV). No position reconstruction; little sensitivity to E requirements.

Braidwood Experiment Projected Uncertainties and Sensitivity 3 year run Baseline Cost and Schedule Estimates Civil Construction (Hilton and Assoc. consulting firm, using U of C seed money) Construction + EDIA Contingency $34M $8.5M $42.5M $18M $5M $23M Detectors (Bartozek engineering, ANL)

Four detectors with veto system + EDIA Contingency Schedule 2004 2005 2007 2009 Engineering/R&D proposal submitted Full proposal submission Project approval; construction start Start datataking Braidwood Engineering / R&D Proposal Multi-institution proposal submitted to NSF and DOE (PI: Blucher, CO-PIs: Shaevitz, Exelon Letter of support: - Enthusiastic about project Bolton, Klein, Fisher) Proposal requests funding to complete the design and engineering of the baseline

project: Civil engineering design leading to RFP for a Design and Build Detector engineering leading to full Design Report Final development of stable Gd loaded scintillator Budget: Civil Engineering Detector Engineering Liquid Scint. Education and Outreach Total $525k $408k $28k $78k $1039k - No security and site access

problems foreseen - 1st step was MOU on bore holes First construction at Braidwood site (December 2004) Using seed money ($100k) from University of Chicago, weve drilled bore holes to full depth (200m) at the near and far shaft positions. Detailed information on geology, ground water, radioactivity, density, etc. Bore hole study provides information needed for underground construction design; reduces required contingency Demonstrates willingness of Exelon to allow construction on their site. Chicago Braidwood Group Activities Software development and detector optimization studies - Matt Worcester co-leads the Braidwood Software and Background Group (with Tim Bolton) Front-end electronics, DAQ, trigger development - Jim Pilcher leads the Braidwood Electronics Group Liquid scintillator test cell

Detector mechanical engineering (Pod): Calibration system and phototube support Braidwood site investigation Small liquid scintillator test cell Phototube Gd Loaded Scintillator Phototube Instrumented with CAMAC ADCs,TDCs, NIM electronics + ATLAS Tile Calorimeter electronics system Weve performed initial studies with cosmics and radioactive sources: Co, AmBe, Cf.

Large test cell with 100 liter Gd-loaded central region under construction ACRYLIC CYLINDER END PLATES MATCH DETECTOR VESSEL THICKNESS 60 20 Student training: KTeV and Braidwood experiments have provided exceptional opportunities for training graduate and undergraduate students. Examples: Val Prasad: 2002 Fermilab Dissertation of the Year award. Now doing atomic physics at Yale. Peter Shawhan: 1999 Fermilab Dissertation of the Year award. Working on

LIGO at Caltech. Abby Kaboth (current undergrad): Working on liquid scintillator studies for Braidwood. Goldwater scholarship winner. David Underwood (current undergrad): Performing measurement of semileptonic charge asymmetry, KL attenuation for analysis Jennifer Seger (current undergrad): Reactor experiment sensitivity studies; KTeV CsI energy calibration CP Group Summary Group is completing KTeV analysis program and starting new program in neutrino oscillation physics. We play a leading role in both experiments. We have concentrated groups efforts on small number of important physics topics that have an extremely broad impact in particle physics. Both KTeV and Braidwood experiments provide exceptional training opportunities for undergraduates, grad students, postdocs, and faculty.

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