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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2010

Recent Progress at the Photon Factory Storage Ring

The present status of the Photon Factory storage ring (PF ring) at High Energy Accelerator Research Organization (KEK), including recent progress for the machine developments, is reported. Due to the establishment of the simultaneous injection to the three rings (PF, HER, LER) from the KEK injector linac since April 2009, the PF ring currently operates almost all the time in a top-up mode available to users at a stored current of 450 mA in multi-bunch mode, and at a stored current of 51 mA in single-bunch mode, except the time while the KEK linac injection to the PF-AR twice daily. The third in-vacuum short gap undulator was installed at PF ring in September 2009.

43 PARTICLE ACCELERATORS↗
DOE OSTI2010

Development of the Short Gap Undulators at the Photon Factory, KEK

Very short-period and in-vacuum type undulators have been developed and installed in the 2.5-GeV Photon Factory storage ring, which was upgraded to enhance the straight sections for insertion devices in 2005. X rays ranging from 2 keV to 15 keV are covered by these undurators with their lower harmonics.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Two-body Final States in Two-photon Processes at Belle

We report studies of various two-body final states produced in gamma-gamma collisions at the KEKB asymmetric-energy e{sup +}e{sup -} collider with the Belle detector. The final states include: {pi}{sup +}{pi}{sup -}, K{sup +}K{sup -}, K{sub S}K{sub S}, {pi}{sup 0}{pi}{sup 0}, {eta}{pi}{sup 0},{eta}{eta} and pp-bar. For the low two-photon center-of-mass energy region, the production of 'f' and 'a' resonances in the mass range 0.98-2.3 GeV is discussed. In the high center-of-mass energy region (W>3 GeV), we compare the energy and angular dependencies of the cross sections with predictions of QCD and other models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Search for leptonic decays of D{sup 0} mesons

We search for the flavor-changing neutral current decays D{sup 0{yields}{mu}+{mu}-} and D{sup 0{yields}}e{sup +}e{sup -}, and for the lepton-flavor violating decays D{sup 0{yields}}e{sup {+-}{mu}{+-}}using 660 fb{sup -1} of data collected with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. We find no evidence for any of these decays. We obtain significantly improved upper limits on the branching fractions: B(D{sup 0{yields}{mu}+{mu}-})<1.4x10{sup -7}, B(D{sup 0{yields}}e{sup +}e{sup -})<7.9x10{sup -8}, and B(D{sup 0{yields}}e{sup +{mu}-})+B(D{sup 0{yields}{mu}+}e{sup -})<2.6x10{sup -7} at 90% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Evidence for B{yields}K{eta}'{gamma} decays at Belle

We present the results of a search for the radiative decay B{yields}K{eta}{sup '{gamma}} and find evidence for B{sup +{yields}}K{sup +{eta}'{gamma}} decays at the 3.3 standard deviation level with a partial branching fraction of (3.6{+-}1.2{+-}0.4)x10{sup -6}, where the first error is statistical and the second systematic. This measurement is restricted to the region of combined K{eta}{sup '} invariant mass less than 3.4 GeV/c{sup 2}. A 90% confidence level upper limit of 6.4x10{sup -6} is obtained for the partial branching fraction of the decay B{sup 0{yields}}K{sup 0{eta}'{gamma}} in the same K{eta}{sup '} invariant mass region. These results are obtained from a 605 fb{sup -1} data sample containing 657x10{sup 6}BB pairs collected at the {Upsilon}(4S) resonance with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Measurement of {Upsilon}(5S) decays to B{sup 0} and B{sup +} mesons

Decays of the {Upsilon}(5S) resonance to channels with B{sup +} and B{sup 0} mesons are studied using a 23.6 fb{sup -1} data sample collected with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. Fully reconstructed B{sup +{yields}}J/{psi}K{sup +}, B{sup 0{yields}}J/{psi}K*{sup 0}, B{sup +{yields}}D{sup 0{pi}+}, and B{sup 0{yields}}D{sup -{pi}+} decays are used to obtain the charged and neutral B production rates per bb event, f(B{sup +})=(72.1{sub -3.8}{sup +3.9{+-}}5.0)% and f(B{sup 0})=(77.0{sub -5.6}{sup +5.8{+-}}6.1)%. Assuming equal rates to B{sup +} and B{sup 0} mesons in all channels produced at the {Upsilon}(5S) energy, we measure the fractions for transitions to two-body and three-body channels with B meson pairs, f(BB)=(5.5{sub -0.9}{sup +1.0{+-}}0.4)%, f(BB*+B*B)=(13.7{+-}1.3{+-}1.1)%, f(B*B*)=(37.5{sub -1.9}{sup +2.1{+-}}3.0)%, f(BB{pi})=(0.0{+-}1.2{+-}0.3)%, f(BB*{pi}+B*B{pi})=(7.3{sub -2.1}{sup +2.3{+-}}0.8)%, and f(B*B*{pi})=(1.0{sub -1.3}{sup +1.4{+-}}0.4)%. The latter three fractions are obtained assuming isospin conservation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Measurements of branching fractions for B{sup 0}{yields}D{sub s}{sup +}{pi}{sup -} and B{sup 0}{yields}D{sub s}{sup +}K{sup -}

We present improved measurements of the branching fractions for the decays B{sup 0}{yields}D{sub s}{sup +}{pi}{sup -} and B{sup 0}{yields}D{sub s}{sup +}K{sup -} using a data sample of 657x10{sup 6} BB events collected at the {Upsilon}(4S) resonance with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. The results are B(B{sup 0}{yields}D{sub s}{sup +}{pi}{sup -})=(1.99{+-}0.26{+-}0.18)x10{sup -5} and B(B{sup 0}{yields}D{sub s}{sup +}K{sup -})=(1.91{+-}0.24{+-}0.17)x10{sup -5}, where the uncertainties are statistical and systematic, respectively. Based on these results, we determine the ratio between amplitudes of the doubly Cabibbo suppressed decay B{sup 0}{yields}D{sup +}{pi}{sup -} and the Cabibbo favored decay B{sup 0}{yields}D{sup -}{pi}{sup +}, R{sub D}{pi}=[1.71{+-}0.11(stat){+-}0.09(syst){+-}0.02(theo)]%, where the last term denotes the theory error.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Measurement of CP violating asymmetries in B{sup 0{yields}}K{sup +}K{sup -}K{sub S}{sup 0} decays with a time-dependent Dalitz approach

We report a measurement of CP violating asymmetries in B{sup 0}(B{sup 0}){yields}K{sup +}K{sup -}K{sub S}{sup 0} decays with a time-dependent Dalitz approach. This analysis is based on a data sample of 657x10{sup 6} BB pairs accumulated at the {Upsilon}(4S) resonance with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. As the result of an unbinned maximum likelihood fit to the selected candidates, the mixing-induced and direct CP violation parameters {phi}{sub 1}{sup eff} and A{sub CP} are obtained for B{sup 0{yields}{phi}}(1020)K{sub S}{sup 0}, B{sup 0{yields}}f{sub 0}(980)K{sub S}{sup 0}, and other B{sup 0{yields}}K{sup +}K{sup -}K{sub S}{sup 0} decays. We find four solutions that describe the data. There are {phi}{sub 1}{sup eff}(B{sup 0{yields}{phi}}(1020)K{sub S}{sup 0})=(32.2{+-}9.0{+-}2.6{+-}1.4) deg.; {phi}{sub 1}{sup eff}(B{sup 0{yields}{phi}}(1020)K{sub S}{sup 0})=(26.2{+-}8.8{+-}2.7{+-}1.2) deg.; {phi}{sub 1}{sup eff}(B{sup 0{yields}{phi}}(1020)K{sub S}{sup 0})=(27.3{+-}8.6{+-}2.8{+-}1.3) deg.; and {phi}{sub 1}{sup eff}(B{sup 0{yields}{phi}}(1020)K{sub S}{sup 0})=(24.3{+-}8.0{+-}2.9{+-}5.2) deg. The values for the CP violating phase in B{sup 0{yields}{phi}}(1020)K{sub S}{sup 0} are similar, but other properties of the Dalitz plot are quite different for the four solutions. These four solutions have consistent {phi}{sub 1}{sup eff} values for all three B-meson decay channels and none of them deviates significantly from the values measured in B{yields}(cc)K{sup 0} decays with the currently available statistics. In addition, we find no significant direct CP violation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Search for the decay K{sub L}{sup 0}{yields}3{gamma}

We performed a search for the decay K{sub L}{sup 0}{yields}3{gamma} with the E391a detector at KEK. In the data accumulated in 2005, no event was observed in the signal region. Based on the assumption of K{sub L}{sup 0}{yields}3{gamma} proceeding via parity-violation, we obtained the single event sensitivity to be (3.23{+-}0.14)x10{sup -8}, and set an upper limit on the branching ratio to be 7.4x10{sup -8} at the 90% confidence level. This is a factor of 3.2 improvement compared to the previous results. The results of K{sub L}{sup 0}{yields}3{gamma} proceeding via parity-conservation were also presented in this paper.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Measurement of the decay B{sup 0}{yields}{pi}{sup -}l{sup +}{nu} and determination of |V{sub ub}|

We present a measurement of the charmless semileptonic decay B{sup 0}{yields}{pi}{sup -}l{sup +}{nu} using a data sample containing 657x10{sup 6} BB events collected with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider operating near the {Upsilon}(4S) resonance. We determine the total branching fraction of the decay, B(B{sup 0}{yields}{pi}{sup -}l{sup +}{nu})=(1.49{+-}0.04(stat){+-}0.07(syst))x10{sup -4}. We also report a new precise measurement of the differential decay rate and extract the Cabibbo-Kobayashi-Maskawa matrix element |V{sub ub}| using model-independent and model-dependent approaches. From a simultaneous fit to the measured differential decay rate and lattice QCD results, we obtain |V{sub ub}|=(3.43{+-}0.33)x10{sup -3}, where the error includes both experimental and theoretical uncertainties.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

First observation of radiative B⁰ → ΦK⁰γ decays and measurements of their time-dependent CP violation

We report the first observation of the radiative decay B⁰→ ΦK⁰γ using a data sample of 772 × 10⁶ BB¯ pairs collected at the (4S) resonance with the Belle detector at the KEKB asymmetric-energy e⁺e⁻ collider. We observe a signal of 37 ± 8 events with a significance of 5.4 standard deviations including systematic uncertainties. The measured branching fraction is B(B⁰→ ΦK⁰γ) = (2.74±0.60±0.32)×10⁻⁶, where the uncertainties are statistical and systematic, respectively. We also report the first measurements of time-dependent CP-violation parameters: S ΦK⁰ S γ = +0.74 ⁺0.72 –1.05 (stat) +0.10 –0.24 (syst) and A ΦK⁰ S γ = +0.35 ± 0.58(stat) +0.23 –0.10 (syst). Furthermore, we measure B(B⁺ → ΦK⁺γ) = (2.48 ± 0.30 ± 0.24) × 10⁻⁶, ACP = –0.03 ± 0.11 ± 0.08 and find that the signal is concentrated in the M ΦK mass region near threshold.

Sahoo, Himansu B.↗
DOE OSTI2011

Observation of B - →$\bar{p}$ΛD 0 at Belle

We study B- meson decays to $\bar{p}$ΛD (*)0 final states using a sample of 657×10 6 B$\bar{B}$ events collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e - collider. The observed branching fraction for B - →$\bar{p}$ΛD 0 is (1.43$+0.28\atop{-0.25}$±0.18)×10 -5 with a significance of 8.1 standard deviations, where the uncertainties are statistical and systematic, respectively. Most of the signal events have the $\bar{p}$ Λ mass peaking near threshold. No significant signal is observed for $\bar{p}$ΛD (*)0 and the corresponding upper limit on the branching fraction is 4.8×10 -5 at the 90% confidence level.

43 PARTICLE ACCELERATORS↗
DOE OSTI2010

Search for CP Violation in the Decays D{sub (s)}{sup +{yields}}K{sub S}{sup 0{pi}+} and D{sub (s)}{sup +{yields}}K{sub S}{sup 0}K{sup +}

We have searched for CP violation in the charmed meson decays D{sub (s)}{sup +{yields}}K{sub S}{sup 0{pi}+} and D{sub (s)}{sup +{yields}}K{sub S}{sup 0}K{sup +} using 673 fb{sup -1} of data collected with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. No evidence for CP violation is observed. We report the most sensitive CP asymmetry measurements to date for these decays: A{sub CP}{sup D+{yields}K}{sub S}{sup 0{pi}+}=(-0.71{+-}0.19{+-}0.20)%, A{sub CP}{sup D}{sub s}{sup +{yields}K}{sub S}{sup 0{pi}+}=(+5.45{+-}2.50{+-}0.33)%, A{sub CP}{sup D+{yields}K}{sub S}{sup 0K+}=(-0.16{+-}0.58{+-}0.25)%, and A{sub CP}{sup D}{sub s}{sup +{yields}K}{sub S}{sup 0K+}=(+0.12{+-}0.36{+-}0.22)%, where the first uncertainties are statistical and the second are systematic.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Five-Body Cluster Structure of the Double-{Lambda} Hypernucleus {sub {Lambda}{Lambda}}{sup 11}Be

Energy levels of the double {Lambda} hypernucleus, {sub {Lambda}{Lambda}}{sup 11}Be are calculated within the framework of a {alpha}{alpha}n{Lambda}{Lambda} five-body model. Interactions between constituent particles are determined so as to reproduce reasonably the observed low-energy properties of the {alpha}{alpha}, {alpha}{alpha}n nuclei and the existing data for {Lambda}-binding energies of the {alpha}{Lambda}, {alpha}{alpha}{Lambda}, {alpha}n{Lambda}, and {alpha}{alpha}n{Lambda} systems. An effective {Lambda}{Lambda} interaction is constructed so as to reproduce, within the {alpha}{Lambda}{Lambda} three-body model, the B{sub {Lambda}{Lambda}}of {sub {Lambda}{Lambda}}{sup 6}He, which was extracted from the emulsion experiment, the NAGARA event. With no adjustable parameters for the {alpha}{alpha}n{Lambda}{Lambda} system, B{sub {Lambda}{Lambda}}of the ground and bound excited states of {sub {Lambda}{Lambda}}{sup 11}Be are calculated with the Gaussian expansion method. The Hida event, recently observed at KEK-E373 experiment, is interpreted as an observation of the ground state of the {sub {Lambda}{Lambda}}{sup 11}Be.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2010

Surface analyses of electropolished niobium samples for superconducting radio frequency cavity

The performance of superconducting radio frequency niobium cavities is sometimes limited by contaminations present on the cavity surface. In the recent years extensive research has been done to enhance the cavity performance by applying improved surface treatments such as mechanical grinding, electropolishing (EP), chemical polishing, tumbling, etc., followed by various rinsing methods such as ultrasonic pure water rinse, alcoholic rinse, high pressure water rinse, hydrogen per oxide rinse, etc. Although good cavity performance has been obtained lately by various post-EP cleaning methods, the detailed nature about the surface contaminants is still not fully characterized. Further efforts in this area are desired. Prior x-ray photoelectron spectroscopy (XPS) analyses of EPed niobium samples treated with fresh EP acid, demonstrated that the surfaces were covered mainly with the niobium oxide (Nb{sub 2}O{sub 5}) along with carbon, in addition a small quantity of sulfur and fluorine were also found in secondary ion mass spectroscopy (SIMS) analysis. In this article, the authors present the analyses of surface contaminations for a series of EPed niobium samples located at various positions of a single cell niobium cavity followed by ultrapure water rinsing as well as our endeavor to understand the aging effect of EP acid solution in terms of contaminations presence at the inner surface of the cavity with the help of surface analytical tools such as XPS, SIMS, and scanning electron microscope at KEK.

36 MATERIALS SCIENCE↗