Jerry Va’vra

Jerry Va’vra
SLAC - Stanford University · retired

PhD

About

1,521
Publications
254,725
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28,122
Citations
Citations since 2016
9 Research Items
8689 Citations
201620172018201920202021202202004006008001,0001,2001,400
201620172018201920202021202202004006008001,0001,2001,400
201620172018201920202021202202004006008001,0001,2001,400
201620172018201920202021202202004006008001,0001,2001,400

Publications

Publications (1,521)
Article
Full-text available
Detector examples discussed: MRPCs, MCP-PMTs, Diamond detectors, SiPMTs, Low and high gain Avalanche diodes (LGADs) and Micromegas. We specially discuss issues such as single pixel vs. multi-pixel tests, small test vs. large physics system results and hidden problems people usually do not want to talk about.
Article
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In this article we review a distinctive type of Cherenkov ring imaging device generically called a DIRC detector. DIRC is an acronym for “Detection of Internally Reflected Cherenkov (Light)”. We briefly discuss how these devices were first motivated and conceived, describe their basic operating principles, their early prototypes, and fabrication R&...
Preprint
Full-text available
Detector examples discussed: MRPCs, MCP-PMTs, Diamond detectors, SiPMTs, Low and high gain Avalanche diodes (LGADs) and Micromegas. We specifically discuss issues such as single pixel vs. multi-pixel tests, small test vs. large physics system results and hidden problems people usually do not want to talk about.
Preprint
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This paper discusses a possible existence of small hydrogen, which may have been created during the Big Bang before formation of normal hydrogen.
Article
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This paper discusses a possible existence of small hydrogen, which may have been created during the Big Bang before formation of normal hydrogen. Keywords: Small hydrogen atom, Dark matter
Article
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t – In this review article we discuss new updates on PID techniques, other than the Cherenkov method. In particular, we discuss recent efforts to develop high resolution timing, placing an emphasis on small scale test results.
Article
In this article. ¹ 1The paper was presented at the RICH 2016 conference, Bled, Slovenia, September 2016. we explore the angular resolution limits attainable in small FDIRC designs taking advantage of the new highly pixelated detectors that are now available. Since the basic FDIRC design concept attains its particle separation performance mostly in...
Article
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This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these...
Article
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In this paper we investigate di-atomic molecules embedded in ice crystals under strain. In this environment coherent vibrations of many OH-bonds may be generated by one WIMP collision. The detection of such multiple-photon signals may provide a signature of a 100~GeV/c${^2}$ WIMP.
Article
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This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C. Please not...
Article
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Dark sectors charged under a new Abelian interaction have recently received much attention in the context of dark matter models. These models introduce a light new mediator, the so-called dark photon (A^{'}), connecting the dark sector to the standard model. We present a search for a dark photon in the reaction e^{+}e^{-}→γA^{'}, A^{'}→e^{+}e^{-},...
Article
We present the final results from a novel Cherenkov imaging detector called the Focusing DIRC (FDIRC). This detector was designed as a full-scale prototype of the particle identification system for the SuperB experiment [1], and comprises 1/12 of the SuperB barrel azimuthal coverage, with partial photodetector and electronics implementation. The pr...
Article
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Recent reference [Vavra, 2014] touched on a possibility that the DAMA experiment [Bernabei, 2013] observes the WIMP via molecular excitations of OH-molecules, left in the NaI(Tl) material as an impurity. Independently of the outcome of this particular investigation, we think that the Dark matter search should be expanded into a domain of detectors...
Article
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The DAMA experiment clearly observes a small oscillatory signal. The observed yearly modulation is in phase with the Earth's motion around the Sun. Recent reference [Vavra, 2014] suggested that the DAMA experiment observes a WIMP of much smaller mass than what Xenon 10, Xenon 100, LUX and CDMS experiments can possibly reach. Scattering would occur...
Article
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These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 8, on the Instrumentation Frontier, discusses the instrumentation needs of future experiments in the Energy, Intensity, and Cosmic Frontiers, promising new t...
Article
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At present there is an e?ort to reconcile the results of the DAMA experiment with those from other Dark Matter experiments such as CoGeNT, CRESST, CDMS, and all LXe experiments. The author suggests a new model describing the Dark Matter signal as the result of collisions of very light (1-to-few GeV/c^2) WIMPs with hydrogen, and compares it with cur...
Article
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We describe searches for B meson decays to the charmless vector-vector final states omega omega and omega phi with 471 x 10^6 B Bbar pairs produced in e+ e- annihilation at sqrt(s) = 10.58 GeV using the BABAR detector at the PEP-II collider at the SLAC National Accelerator Laboratory. We measure the branching fraction B(B0 --> omega omega) = (1.2 +...
Article
Detectors of Internally Reflected Cherenkov light (DIRC) are powerful devices for charged particle identification (PID). Indeed, the primary detector to separate kaons and pions up to few GeV/c in the barrel region of the BABAR experiment was based on the DIRC technology and performed extremely well over almost a decade of operation. In the first p...
Article
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Sensors play a key role in detecting both charged particles and photons for all three frontiers in Particle Physics. The signals from an individual sensor that can be used include ionization deposited, phonons created, or light emitted from excitations of the material. The individual sensors are then typically arrayed for detection of individual pa...
Article
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We measure the mass difference Δm_{0} between the D^{*}(2010)^{+} and the D^{0} and the natural linewidth Γ of the transition D^{*}(2010)^{+}→D^{0}π^{+}. The data were recorded with the BABAR detector at center-of-mass energies at and near the Υ(4S) resonance, and correspond to an integrated luminosity of approximately 477 fb^{-1}. The D^{0} is rec...
Article
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We present results of a search for CP violation in B^{0}- B[over ¯]^{0} mixing with the BABAR detector. We select a sample of B^{0}→D^{*-}Xℓ^{+}ν decays with a partial reconstruction method and use kaon tagging to assess the flavor of the other B meson in the event. We determine the CP violating asymmetry A_{CP}≡[N(B^{0}B^{0})-N(B[over ¯]^{0}B[over...
Article
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An overview of the electronics chains for the two charged particle identification (PID) detectors of the SuperB experiment is presented. The PID group is designing different detectors for the barrel (FDIRC) and forward (FTOF) regions. Both are based on time measurements, respectively in the 100 ps and 10 ps rms resolution domains.
Conference Paper
An overview of ongoing studies on the Hamamatsu H-8500 Multi-Anode Photomultiplier (MaPMT) is presented. This device will be used for the FDIRC Particle Identification Detector (PID) of the SuperB experiment. The H-8500 MaPMT has been chosen for its excellent single photon timing capabilities and its highly pixilated design. Results on timing studi...
Article
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In this Technical Design Report (TDR) we describe the SuperB detector that was to be installed on the SuperB e+e- high luminosity collider. The SuperB asymmetric collider, which was to be constructed on the Tor Vergata campus near the INFN Frascati National Laboratory, was designed to operate both at the Upsilon(4S) center-of-mass energy with a lum...
Article
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The first gamma-ray line originating from outside the solar system that was ever detected is the 511keV emission from the center of our Galaxy. The accepted explanation of this signal is the annihilation of electrons and positrons. However, despite 30 years of intense theoretical and observational investigation, the main sources of positrons have n...
Article
We present a detailed study of a novel Cherenkov imaging detector called the Focusing DIRC (FDIRC) with waveform digitizing electronics. In this study, the FDIRC prototype has been instrumented with seven Hamamatsu H-8500 MaPMTs. Waveforms from 384 pixels are digitized with waveform sampling electronics based on the BLAB2 ASIC, operating at a sampl...
Article
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We study the decay $\bar{B}^{0}\rightarrow\Lambda_{c}^{+}\bar{p}\pi^{+}\pi^{-}$, reconstructing the \Lambda_{c}^{+} baryon in the $p K^{-}\pi^{+}$ mode, using a data sample of $467\times 10^{6}$ $B\bar{B}$ pairs collected with the BaBar detector at the PEP-2 storage rings at SLAC. We measure branching fractions for decays with intermediate $\Sigma_...
Article
An overview of ongoing studies on the Hamamatsu H-8500 Multi-Anode Photomultiplier (MaPMT) is presented. This device will be used for the FDIRC Particle Identification Detector (PID) of the SuperB experiment. The H-8500 MaPMT has been chosen for its excellent single photon timing capabilities and its highly pixilated design. Results on timing studi...
Article
Full-text available
We report on a search for direct CP asymmetry in the singly Cabibbo-suppressed decay D+- --> K+ K- pi+- using a data sample of 476 fb-1 accumulated with the BaBar detector running at and just below the Y(4S) resonance. The CP-violating decay rate asymmetry A_CP is determined to be (0.35 +- 0.30 +- 0.15)%. Model-dependent and model-independent Dalit...
Article
The DIRC-like TOF detector is a ring imaging Cherenkov counter, designed for the SuperB experiment, which uses time-of-flight to identify charged particles. A prototype of this device was constructed and installed in the SLAC Cosmic Ray Telescope for timing measurement. A time resolution of about 70 ps per photoelectron was obtained, in agreement w...
Article
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Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavor states (B^{0} or B[over ¯]^{0}), and J/ψK_{L}^{0} or cc[over ¯]K_{S}^{0} final states (referred to as B_{+} or B_{-}), allow comparis...
Article
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The photon spectrum in the inclusive electromagnetic radiative decays of the B meson, B→X_{s}γ plus B→X_{d}γ, is studied using a data sample of (382.8±4.2)×10^{6}Υ(4S)→BB[over ¯] decays collected by the BABAR experiment at SLAC. The spectrum is used to extract the branching fraction B(B→X_{s}γ)=(3.21±0.33)×10^{-4} for E_{γ}>1.8  GeV and the direct...
Article
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We use 429 fb-1 of e+e- collision data collected at the Υ(4S) resonance with the BABAR detector to measure the radiative transition rate of b→sγ with a sum of 38 exclusive final states. The inclusive branching fraction with a minimum photon energy of 1.9 GeV is found to be B(B̅ →Xsγ)=(3.29±0.19±0.48)×10-4 where the first uncertainty is statistical...
Article
We study the process e+e-→J/ψπ+π- with initial-state-radiation events produced at the PEP-II asymmetric-energy collider. The data were recorded with the BABAR detector at center-of-mass energies 10.58 and 10.54 GeV, and correspond to an integrated luminosity of 454 fb-1. We investigate the J/ψπ+π- mass distribution in the region from 3.5 to 5.5 GeV...
Article
Based on the full BABAR data sample, we report improved measurements of the ratios R(D^{(*)})=B(B[over ¯]→D^{(*)}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]→D^{(*)}ℓ_{ℓ}^{-}ν[over ¯]_{ℓ}), where ℓ is either e or μ. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D)=0.440±0.058±0.042 and R(D^{*})=0.332±...
Article
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A precise measurement of the cross section of the process e+e-→π+π-(γ) from threshold to an energy of 3 GeV is obtained with the initial-state radiation (ISR) method using 232 fb-1 of data collected with the BABAR detector at e+e- center-of-mass energies near 10.6 GeV. The ISR luminosity is determined from a study of the leptonic process e+e-→μ+μ-(...
Article
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In a sample of 471×106 BB̅ events collected with the BABAR detector at the PEP-II e+e- collider we study the rare decays B→K(*)ℓ+ℓ-, where ℓ+ℓ- is either e+e- or μ+μ-. We report results on partial branching fractions and isospin asymmetries in seven bins of dilepton mass-squared. We further present CP and lepton-flavor asymmetries for dilepton mass...
Article
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We report measurements of partial branching fractions for inclusive charmless semileptonic B decays B̅ →Xuℓν̅ and the determination of the Cabibbo–Kobayashi–Maskawa (CKM) matrix element |Vub|. The analysis is based on a sample of 467×106 Υ(4S)→BB̅ decays recorded with the BABAR detector at the PEP-II e+e- storage rings. We select events in which th...
Article
Full-text available
We report the results of a study of the exclusive charmless semileptonic decays, B^0 --> pi^- l^+ nu, B^+ --> pi^0 l^+ nu, B^+ --> omega l^+ nu, B^+ --> eta l^+ nu and B^+ --> eta^' l^+ nu, (l = e or mu) undertaken with approximately 462x10^6 B\bar{B} pairs collected at the Upsilon(4S) resonance with the BABAR detector. The analysis uses events in...
Article
We study the processes e+e-→K+K-π+π-γ, K+K-π0π0γ, and K+K-K+K-γ, where the photon is radiated from the initial state. About 84 000, 8000, and 4200 fully reconstructed events, respectively, are selected from 454 fb-1 of BABAR data. The invariant mass of the hadronic final state defines the e+e- center-of-mass energy, so that the K+K-π+π-γ data can b...
Article
Full-text available
Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time reversal violation. The decays of entangled neutral B mesons into definite flavor states ($B^0$ or $\bar{B}^0$), and $J/\psi K_S^0$ or $c\bar{c} K_S^0$ final states (referred to as $B_+$ or $B_-$), allow comparisons...
Article
Full-text available
We present a search for the lepton flavor violating decay modes B±→h±τℓ (h=K, π; ℓ=e, μ) using the BABAR data sample, which corresponds to 472×106 BB̅ pairs. The search uses events where one B meson is fully reconstructed in one of several hadronic final states. Using the momenta of the reconstructed B, h, and ℓ candidates, we are able to fully det...
Article
We perform amplitude analyses of the decays B0→K+K-KS0, B+→K+K-K+, and B+→KS0KS0K+, and measure CP-violating parameters and partial branching fractions. The results are based on a data sample of approximately 470×106 BB̅ decays, collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the SLAC National Accelerator Laboratory....
Article
We present results for B-meson decay modes involving a charm meson, protons, and pions using 455×106 BB̅ pairs recorded by the BaBar detector at the SLAC PEP-II asymmetric-energy e+e- collider. The branching fractions are measured for the following ten decays: B̅ 0→D0pp̅ , B̅ 0→D*0pp̅ , B̅ 0→D+pp̅ π-, B̅ 0→D*+pp̅ π-, B-→D0pp̅ π-, B-→D*0pp̅ π-, B̅ 0...
Article
The DIRC-like time-of-flight detector (FTOF) is a ring imaging Cherenkov counter designed to improve the charged particle identification on the forward side of SuperB. Here we review the main characteristics of this device, summarize the results of a prototype test done last year in the SLAC Cosmic Ray Telescope and present the future steps needed...
Article
Full-text available
We present branching fraction measurements for the decays B0→ρ0K*0, B0→f0K*0, and B0→ρ-K*+, where K* is an S-wave (Kπ)0* or a K*(892) meson; we also measure B0→f0K2*(1430)0. For the K*(892) channels, we report measurements of longitudinal polarization fractions (for ρ final states) and direct CP violation asymmetries. These results are obtained fro...
Article
Full-text available
We present the first results on the Dalitz-plot structure and improved measurements of the time-dependent CP-violation parameters of the process B0→KS0KS0KS0 obtained using 468×106 BB̅ decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The Dalitz-plot structure is probed by a time-integrated amplitude analys...
Article
We search for the Z1(4050)+ and Z2(4250)+ states, reported by the Belle Collaboration, decaying to χc1π+ in the decays B̅ 0→χc1K-π+ and B+→χc1KS0π+ where χc1→J/ψγ. The data were collected with the BABAR detector at the SLAC PEP-II asymmetric-energy e+e- collider operating at center-of-mass energy 10.58 GeV, and correspond to an integrated luminosit...
Article
Full-text available
We have searched for the lepton-number violating processes B+ -> h(-)l(+)l(+) with h(-) = K-/pi(-) and l(+) = e(+)/mu(+), using a sample of 471 +/- 3 million B (B) over bar events collected with the BABAR detector at the PEP-II e(+)e(-) collider at the SLAC National Accelerator Laboratory. We find no evidence for these decays and place 90%-confiden...
Article
Full-text available
We study the process e+e- -> pi+pi-pi+pi-gamma, with a photon emitted from the initial-state electron or positron, using 454.3 fb^-1 of data collected with the BABAR detector at SLAC, corresponding to approximately 260,000 signal events. We use these data to extract the non-radiative sigma(e+e- ->pi+pi-pi+pi-) cross section in the energy range from...
Article
We report updated branching fraction measurements of the color-suppressed decays B̅ 0→D0π0, D*0π0, D0η, D*0η, D0ω, D*0ω, D0η′, and D*0η′. We measure the branching fractions (×10-4): B(B̅ 0→D0π0)=2.69±0.09±0.13, B(B̅ 0→D*0π0)=3.05±0.14±0.28, B(B̅ 0→D0η)=2.53±0.09±0.11, B(B̅ 0→D*0η)=2.69±0.14±0.23, B(B̅ 0→D0ω)=2.57±0.11±0.14, B(B̅ 0→D*0ω)=4.55±0.24±0...
Article
Full-text available
We report updated branching fraction measurements of the color-suppressed decays B̅ 0→D0π0, D*0π0, D0η, D*0η, D0ω, D*0ω, D0η′, and D*0η′. We measure the branching fractions (×10-4): B(B̅ 0→D0π0)=2.69±0.09±0.13, B(B̅ 0→D*0π0)=3.05±0.14±0.28, B(B̅ 0→D0η)=2.53±0.09±0.11, B(B̅ 0→D*0η)=2.69±0.14±0.23, B(B̅ 0→D0ω)=2.57±0.11±0.14, B(B̅ 0→D*0ω)=4.55±0.24±0...
Article
We report an analysis of charmless hadronic decays of charged B mesons to the final state K+π0π0, using a data sample of (470.9±2.8)×106 BB̅ events collected with the BABAR detector at the Υ(4S) resonance. We observe an excess of signal events, with a significance above 10 standard deviations including systematic uncertainties, and measure the bran...
Article
We search for hadronic decays of a light Higgs boson (A(0)) produced in radiative decays of an Υ(2S) or Υ(3S) meson, Υ→γA(0). The data have been recorded by the BABAR experiment at the Υ(3S) and Υ(2S) center-of-mass energies and include (121.3±1.2)×10(6) Υ(3S) and (98.3±0.9)×10(6) Υ(2S) mesons. No significant signal is observed. We set 90% confiden...
Article
We study the Υ(3S,2S)→ηΥ(1S) and Υ(3S,2S)→π+π-Υ(1S) transitions with 122×106Υ(3S) and 100×106Υ(2S) mesons collected by the BABAR detector at the PEP-II asymmetric-energy e+e- collider. We measure B[Υ(2S)→ηΥ(1S)]=(2.39±0.31(stat.)±0.14(syst.))×10-4 and Γ[Υ(2S)→ηΥ(1S)]/Γ[Υ(2S)→π+π-Υ(1S)]=(1.35±0.17(stat.)±0.08(syst.))×10-3. We find no evidence for Υ(...
Article
Full-text available
We search for the rare decay of the D0 meson to two photons, D0→γγ, and present a measurement of the branching fraction for a D0 meson decaying to two neutral pions, B(D0→π0π0). The data sample analyzed corresponds to an integrated luminosity of 470.5 fb-1 collected by the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We pla...
Article
Full-text available
We report a measurement of the inclusive semileptonic branching fraction of the B_s meson using data collected with the BaBar detector in the center-of-mass (CM) energy region above the Upsilon(4S) resonance. We use the inclusive yield of phi mesons and the phi yield in association with a high-momentum lepton to perform a simultaneous measurement o...
Article
Full-text available
We search for hadronic decays of a light Higgs boson (A0) produced in radiative decays of an Upsilon(2S) or Upsilon(3S) meson, Upsilon --> gamma A0. The data have been recorded by the BABAR experiment at the Upsilon(3S) and Upsilon(2S) center of mass energies, and include (121.3 \pm 1.2) x 10^6 Upsilon(3S) and (98.3 \pm 0.9) x 10^6 Upsilon(2S) meso...