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Search Results: 1 - 10 of 191289 matches for " D. Androic "
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A Large Solid Angle Study of Pion Absorption on He3
LADS collaboration,T. Alteholz,D. Androic,G. Backenstoss,D. Bosnar,H. Breuer,A. Brkovic,H. Dobbeling,T. Dooling,W. Fong,M. Furic,P. A. M. Gram,N. K. Gregory,J. P. Haas,A. Hoffart,C. H. Q. Ingram,A. Klein,K. Koch,J. Kohler,B. Kotlinski,M. Kroedel,G. Kyle,A. Lehmann,Z. N. Lin,G. Mahl,A. O. Mateos,K. Michaelian,S. Mukhopadhyay,T. Petkovic,R. P. Redwine,D. Rowntree,R. Schumacher,U. Sennhauser,N. Simicevic,F. D. Smit,G. van der Steenhoven,D. R. Tieger,R. Trezeciak,H. Ullrich,M. Wang,M. H. Wang,H. J. Weyer,M. Wildi,K. E. Wilson
Physics , 1994, DOI: 10.1103/PhysRevLett.73.1336
Abstract: Measurements have been made of pi+ absorption on He3 at T_pi+ = 118, 162, and 239 MeV using the Large Acceptance Detector System (LADS). The nearly 4pi solid angle coverage of this detector minimizes uncertainties associated with extrapolations over unmeasured regions of phase space. The total absorption cross section is reported. In addition, the total cross section is divided into components in which only two or all three nucleons play a significant role in the process. These are the first direct measurements of the total and three nucleon absorption cross sections.
Targeting cyclin B1 inhibits proliferation and sensitizes breast cancer cells to taxol
Ilija Androic, Andrea Kr?mer, Ruilan Yan, Franz R?del, Regine G?tje, Manfred Kaufmann, Klaus Strebhardt, Juping Yuan
BMC Cancer , 2008, DOI: 10.1186/1471-2407-8-391
Abstract: In order to explore cyclin B1 as a potential target for gynecological cancer therapy, we studied the effect of small interfering RNA (siRNA) on different gynecological cancer cell lines by monitoring their proliferation rate, cell cycle profile, protein expression and activity, apoptosis induction and colony formation. Tumor formation in vivo was examined using mouse xenograft models.Downregulation of cyclin B1 inhibited proliferation of several breast and cervical cancer cell lines including MCF-7, BT-474, SK-BR-3, MDA-MB-231 and HeLa. After combining cyclin B1 siRNA with taxol, we observed an increased apoptotic rate accompanied by an enhanced antiproliferative effect in breast cancer cells. Furthermore, control HeLa cells were progressively growing, whereas the tumor growth of HeLa cells pre-treated with cyclin B1 siRNA was strongly inhibited in nude mice, indicating that cyclin B1 is indispensable for tumor growth in vivo.Our data support the notion of cyclin B1 being essential for survival and proliferation of gynecological cancer cells. Concordantly, knockdown of cyclin B1 inhibits proliferation in vitro as well as in vivo. Moreover, targeting cyclin B1 sensitizes breast cancer cells to taxol, suggesting that specific cyclin B1 targeting is an attractive strategy for the combination with conventionally used agents in gynecological cancer therapy.Breast and cervical cancers are the most frequent malignancies in women worldwide [1,2]. Uncontrolled cell proliferation, which is associated with the loss of the proper cell cycle control, is a prominent feature in these cancers. The cell cycle is controlled by a highly conserved family of cyclin-dependent kinases (Cdks) and their regulatory subunits cyclins. Among the cyclins, cyclin B1 plays a pivotal role as a regulatory subunit for Cdk1, which is indispensable for the transition from G2 phase to mitosis. Overexpression of cyclin B1 has been reported in various human tumors, such as breast cancer, cervical cancer,
Hypernuclear Spectroscopy using the (e,e'K+) Reaction
L. Yuan,M. Sarsour,T. Miyoshi,Z. Zhu,A. Ahmindouch,D. Androic,T. Angelescu,R. Asaturyan,S. Avery,O. K. Baker,I. Betovic,H. Breuer,R. Carlini,J. Cha,R. Chrien M. Christy,L. Cole,S. Danagoulian,D. Dehnhard,M. Elaasar,A. Empl,R. Ent,H. Fenker,Y. Fujii,M. Furic,L. Gan,K. Garrow,A. Gasparian,P. Gueye,M. harvey,O. Hashimoto,W. Hinton,B. Hu,E. Hungerford,C. Jackson,K. Johnston,H. Juengst,C. Keppel,K. Lan,Y. Liang,V. P. Likhachev,J. H. Liu,D. Mack,A. Margaryan,P. markowitz,H. Mkrtchyan,S. N. Nakamura,T. Petkovic,J. Reinhold,J. Roche,Y. Sato,R. Sawafta,N. Simicevic,G. Smith,S. Stepanyan,V. Tadevosyan,T. Takahashi,K. Tanida,L. Tang,M. Ukai,A. Uzzle,W. Vulcan,S. Wells,S. Wood,G. Xu,H. Yamaguchi,C. Yan
Physics , 2004, DOI: 10.1103/PhysRevC.73.044607
Abstract: A pioneering experiment in Lambda hypernuclear spectroscopy, undertaken at the Thomas Jefferson National Accelerator Facility (Jlab), was recently reported. The experiment used the high- precision, continuous electron beam at Jlab, and a special arrangement of spectrometer magnets to measure the spectrum from {nat}C and 7Li targets using the (e,e' K+)reaction. The 12B hypernuclear spectrum was previously published. This experiment is now reported in more detail, with improved results for the 12B hypernuclear spectrum. In addition, unpublished results of the 7He hypernuclear spectrum are also shown. This later spectrum indicates the need for a more detailed few-body calculation of the hypernucleus and the reaction process. The success of this experiment demonstrates that the (e,e'K+) reaction can be effectively used as a high resolution tool to study hypernuclear spectra, ant its use should be vigorously pursued.
First Determination of the Weak Charge of the Proton
Qweak Collaboration,D. Androic,D. S. Armstrong,A. Asaturyan,T. Averett,J. Balewski,J. Beaufait,R. S. Beminiwattha,J. Benesch,F. Benmokhtar,J. Birchall,R. D. Carlini,G. D. Cates,J. C. Cornejo,S. Covrig,M. M. Dalton,C. A. Davis,W. Deconinck,J. Diefenbach,J. F. Dowd,J. A. Dunne,D. Dutta,W. S. Duvall,M. Elaasar,W. R. Falk,J. M. Finn,T. Forest,D. Gaskell,M. T. W. Gericke,J. Grames,V. M. Gray,K. Grimm,F. Guo,J. R. Hoskins,K. Johnston,D. Jones,M. Jones,R. Jones,M. Kargiantoulakis,P. M. King,E. Korkmaz,S. Kowalski,J. Leacock,J. Leckey,A. R. Lee,J. H. Lee,L. Lee,S. MacEwan,D. Mack,J. A. Magee,R. Mahurin,J. Mammei,J. W. Martin,M. J. McHugh,D. Meekins,J. Mei,R. Michaels,A. Micherdzinska,A. Mkrtchyan,H. Mkrtchyan,N. Morgan,K. E. Myers,A. Narayan,L. Z. Ndukum,V. Nelyubin,Nuruzzaman,W. T. H van Oers,A. K. Opper,S. A. Page,J. Pan,K. D. Paschke,S. K. Phillips,M. L. Pitt,M. Poelker,J. F. Rajotte,W. D. Ramsay,J. Roche,B. Sawatzky,T. Seva,M. H. Shabestari,R. Silwal,N. Simicevic,G. R. Smith,P. Solvignon,D. T. Spayde,A. Subedi,R. Subedi,R. Suleiman,V. Tadevosyan,W. A. Tobias,V. Tvaskis,B. Waidyawansa,P. Wang,S. P. Wells,S. A. Wood,S. Yang,R. D. Young,S. Zhamkochyan
Physics , 2013, DOI: 10.1103/PhysRevLett.111.141803
Abstract: The Qweak experiment has measured the parity-violating asymmetry in polarized e-p elastic scattering at Q^2 = 0.025(GeV/c)^2, employing 145 microamps of 89% longitudinally polarized electrons on a 34.4cm long liquid hydrogen target at Jefferson Lab. The results of the experiment's commissioning run are reported here, constituting approximately 4% of the data collected in the experiment. From these initial results the measured asymmetry is Aep = -279 +- 35 (statistics) +- 31 (systematics) ppb, which is the smallest and most precise asymmetry ever measured in polarized e-p scattering. The small Q^2 of this experiment has made possible the first determination of the weak charge of the proton, QpW, by incorporating earlier parity-violating electron scattering (PVES) data at higher Q^2 to constrain hadronic corrections. The value of QpW obtained in this way is QpW(PVES) = 0.064 +- 0.012, in good agreement with the Standard Model prediction of QpW(SM) = 0.0710 +- 0.0007. When this result is further combined with the Cs atomic parity violation (APV) measurement, significant constraints on the weak charges of the up and down quarks can also be extracted. That PVES+APV analysis reveals the neutron's weak charge to be QnW(PVES+APV) = -0.975 +- 0.010.
Early Results from the Qweak Experiment
D. Androic,D. S. Armstrong,A. Asaturyan,T. Averett,J. Balewski,J. Beaufait,R. S. Beminiwattha,J. Benesch,F. Benmokhtar,J. Birchall,R. D. Carlini,G. D. Cates,J. C. Cornejo,S. Covrig,M. M. Dalton,C. A. Davis,W. Deconinck,J. Diefenbach,J. F. Dowd,J. A. Dunne,D. Dutta,W. S. Duvall,M. Elaasar,W. R. Falk,J. M. Finn,T. Forest,D. Gaskel,M. T. W. Gericke,J. Grames,V. M. Gray,K. Grimm,F. Guo,J. R. Hoskins,K. Johnston,D. Jones,M. Jones,R. Jones,M. Kargiantoulakis,P. M. King,E. Korkmaz,S. Kowalski,J. Leacock,J. Leckey,A. R. Lee,J. H. Lee,L. Lee,S. MacEwan,D. Mack,J. A. Magee,R. Mahurin,J. Mammei,J. Martin,M. J. McHugh,D. Meekins,J. Mei,R. Michaels,A. Micherdzinska,A. Mkrtchyan,H. Mkrtchyan,N. Morgan,K. E. Myers,A. Narayan,L. Z. Ndukum,V. Nelyubin,Nuruzzaman,W. T. H van Oers,A. K. Opper,S. A. Page,J. Pan,K. Paschke,S. K. Phillips,M. L. Pitt,M. Poelker,J. F. Rajotte,W. D. Ramsay,J. Roche,B. Sawatzky,T. Seva,M. H. Shabestari,R. Silwal,N. Simicevic,G. R. Smith,P. Solvignon,D. T. Spayde,A. Subedi,R. Subedi,R. Suleiman,V. Tadevosyan,W. A. Tobias,V. Tvaskis,B. Waidyawansa,P. Wang,S. P. Wells,S. A. Wood,S. Yang,R. D. Young,S. Zhamkochyan
Physics , 2013, DOI: 10.1051/epjconf/20146605002
Abstract: A subset of results from the recently completed Jefferson Lab Qweak experiment are reported. This experiment, sensitive to physics beyond the Standard Model, exploits the small parity-violating asymmetry in elastic ep scattering to provide the first determination of the protons weak charge Qweak(p). The experiment employed a 180 uA longitudinally polarized 1.16 GeV electron beam on a 35 cm long liquid hydrogen target. Scattered electrons corresponding to Q2 of 0.025 GeV2 were detected in eight Cerenkov detectors arrayed symmetrically around the beam axis. The goals of the experiment were to provide a measure of Qweak(p) to 4.2 percent (combined statistical and systematic error), which implies a measure of sin2(thetaw) at the level of 0.3 percent, and to help constrain the vector weak quark charges C1u and C1d. The experimental method is described, with particular focus on the challenges associated with the worlds highest power LH2 target. The new constraints on C1u and C1d provided by the subset of the experiments data analyzed to date will also be shown, together with the extracted weak charge of the neutron.
First Measurement of the Neutral Current Excitation of the Delta Resonance on a Proton Target
G0 Collaboration,D. Androic,D. S. Armstrong,J. Arvieux,S. L. Bailey,D. H. Beck,E. J. Beise,J. Benesch,F. Benmokhtar,L. Bimbot,J. Birchall,P. Bosted,H. Breuer,C. L. Capuano,Y. -C. Chao,A. Coppens,C. A. Davis,C. Ellis,G. Flores,G. Franklin,C. Furget,D. Gaskell,J. Grames,M. T. W. Gericke,G. Guillard,J. Hansknecht,T. Horn,M. K. Jones,P. M. King,W. Korsch,S. Kox,L. Lee,J. Liu,A. Lung,J. Mammei,J. W. Martin,R. D. McKeown,A. Micherdzinska,M. Mihovilovic,H. Mkrtchyan,M. Muether,S. A. Page,V. Papavassiliou,S. F. Pate,S. K. Phillips,P. Pillot,M. L. Pitt,M. Poelker,B. Quinn,W. D. Ramsay,J. -S. Real,J. Roche,P. Roos,J. Schaub,T. Seva,N. Simicevic,G. R. Smith,D. T. Spayde,M. Stutzman,R. Suleiman,V. Tadevosyan,W. T. H. van Oers,M. Versteegen,E. Voutier,W. Vulcan,S. P. Wells,S. E. Williamson,S. A. Wood
Physics , 2012,
Abstract: The parity-violating asymmetry arising from inelastic electron-nucleon scattering at backward angle (~95 degrees) near the Delta(1232) resonance has been measured using a hydrogen target. From this asymmetry, we extracted the axial transition form factor G^A_{N\Delta}, a function of the axial Adler form factors C^A_i. Though G^A_{N\Delta} has been previously studied using charged current reactions, this is the first measurement of the weak neutral current excitation of the Delta using a proton target. For Q^2 = 0.34 (GeV/c)^2 and W = 1.18 GeV, the asymmetry was measured to be -33.4 \pm (5.3)_{stat} \pm (5.1)_{sys} ppm. The value of G^A_{N\Delta} determined from the hydrogen asymmetry was -0.05 \pm (0.35)_{stat} \pm (0.34)_{sys} \pm (0.06)_{theory}. These findings agree within errors with theoretical predictions for both the total asymmetry and the form factor. In addition to the hydrogen measurement, the asymmetry was measured at the same kinematics using a deuterium target. The asymmetry for deuterium was determined to be -43.6 \pm (14.6)_{stat} \pm (6.2)_{sys} ppm.
The Q_weak Experimental Apparatus
Qweak Collaboration,T. Allison,M. Anderson,D. Androic,D. S. Armstrong,A. Asaturyan,T. D. Averett,R. Averill,J. Balewski,J. Beaufait,R. S. Beminiwattha,J. Benesch,F. Benmokhtar,J. Bessuille,J. Birchall,E. Bonnell,J. Bowman,P. Brindza,D. B. Brown,R. D. Carlini,G. D. Cates,B. Cavness,G. Clark,J. C. Cornejo,S. Covrig Dusa,M. M. Dalton,C. A. Davis,D. C. Dean,W. Deconinck,J. Diefenbach,K. Dow,J. F. Dowd,J. A. Dunne,D. Dutta,W. S. Duvall,J. R. Echols,M. Elaasar,W. R. Falk,K. D. Finelli,J. M. Finn,D. Gaskell,M. T. W. Gericke,J. Grames,V. M. Gray,K. Grimm,F. Guo,J. Hansknecht,D. J. Harrison,E. Henderson,J. R. Hoskins,E. Ihloff,K. Johnston,D. Jones,M. Jones,R. Jones,M. Kargiantoulakis,J. Kelsey,N. Khan,P. M. King,E. Korkmaz,S. Kowalski,A. Kubera,J. Leacock,J. P. Leckey,A. R. Lee,J. H. Lee,L. Lee,Y. Liang,S. MacEwan,D. Mack,J. A. Magee,R. Mahurin,J. Mammei,J. W. Martin,A. McCreary,M. H. McDonald,M. J. McHugh,P. Medeiros,D. Meekins,J. Mei,R. Michaels,A. Micherdzinska,A. Mkrtchyan,H. Mkrtchyan,N. Morgan,J. Musson,K. E. Mesick,A. Narayan,L. Z. Ndukum,V. Nelyubin,Nuruzzaman,W. T. H. van Oers,A. K. Opper,S. A. Page,J. Pan,K. D. Paschke,S. K. Phillips,M. L. Pitt,M. Poelker,J. F. Rajotte,W. D. Ramsay,W. R. Roberts,J. Roche,P. W. Rose,B. Sawatzky,T. Seva,M. H. Shabestari,R. Silwal,N. Simicevic,G. R. Smith,S. Sobczynski,P. Solvignon,D. T. Spayde,B. Stokes,D. W. Storey,A. Subedi,R. Subedi,R. Suleiman,V. Tadevosyan,W. A. Tobias,V. Tvaskis,E. Urban,B. Waidyawansa,P. Wang,S. P. Wells,S. A. Wood
Physics , 2014,
Abstract: The Jefferson Lab Q_weak experiment determined the weak charge of the proton by measuring the parity-violating elastic scattering asymmetry of longitudinally polarized electrons from an unpolarized liquid hydrogen target at small momentum transfer. A custom apparatus was designed for this experiment to meet the technical challenges presented by the smallest and most precise ${\vec{e}}$p asymmetry ever measured. Technical milestones were achieved at Jefferson Lab in target power, beam current, beam helicity reversal rate, polarimetry, detected rates, and control of helicity-correlated beam properties. The experiment employed 180 microA of 89% longitudinally polarized electrons whose helicity was reversed 960 times per second. The electrons were accelerated to 1.16 GeV and directed to a beamline with extensive instrumentation to measure helicity-correlated beam properties that can induce false asymmetries. Moller and Compton polarimetry were used to measure the electron beam polarization to better than 1%. The electron beam was incident on a 34.4 cm liquid hydrogen target. After passing through a triple collimator system, scattered electrons between 5.8 degrees and 11.6 degrees were bent in the toroidal magnetic field of a resistive copper-coil magnet. The electrons inside this acceptance were focused onto eight fused silica Cerenkov detectors arrayed symmetrically around the beam axis. A total scattered electron rate of about 7 GHz was incident on the detector array. The detectors were read out in integrating mode by custom-built low-noise pre-amplifiers and 18-bit sampling ADC modules. The momentum transfer Q^2 = 0.025 GeV^2 was determined using dedicated low-current (~100 pA) measurements with a set of drift chambers before (and a set of drift chambers and trigger scintillation counters after) the toroidal magnet.
Observation of the Helium 7 Lambda hypernucleus by the (e,e'K+) reaction
S. N. Nakamura,A. Matsumura,Y. Okayasu,T. Seva,V. M. Rodriguez,P. Baturin,L. Yuan,A. Acha,A. Ahmidouch,D. Androic,A. Asaturyan,R. Asaturyan,O. K. Baker,F. Benmokhtar,P. Bosted,R. Carlini,C. Chen,M. Christy,L. Cole,S. Danagoulian,A. Daniel,V. Dharmawardane,K. Egiyan,M. Elaasar,R. Ent,H. Fenker,Y. Fujii,M. Furic,L. Gan,D. Gaskell,A. Gasparian,E. F. Gibson,T. Gogami,P. Gueye,Y. Han,O. Hashimoto,E. Hiyama,D. Honda,T. Horn,B. Hu,Ed V. Hungerford,C. Jayalath,M. Jones,K. Johnston,N. Kalantarians,H. Kanda,M. Kaneta,F. Kato,S. Kato,D. Kawama,C. Keppel,K. J. Lan,W. Luo,D. Mack,K. Maeda,S. Malace,A. Margaryan,G. Marikyan,P. Markowitz,T. Maruta,N. Maruyama,T. Miyoshi,A. Mkrtchyan,H. Mkrtchyan,S. Nagao,T. Navasardyan,G. Niculescu,M. -I. Niculescu,H. Nomura,K. Nonaka,A. Ohtani,M. Oyamada,N. Perez,T. Petkovic,S. Randeniya,J. Reinhold,J. Roche,Y. Sato,E. K. Segbefia,N. Simicevic,G. Smith,Y. Song,M. Sumihama,V. Tadevosyan,T. Takahashi,L. Tang,K. Tsukada,V. Tvaskis,W. Vulcan,S. Wells,S. A. Wood,C. Yan,S. Zhamkochyan
Physics , 2012, DOI: 10.1103/PhysRevLett.110.012502
Abstract: An experiment with a newly developed high-resolution kaon spectrometer (HKS) and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab (JLab). The ground state of a neutron-rich hypernucleus, He 7 Lambda, was observed for the first time with the (e,e'K+) reaction with an energy resolution of ~0.6 MeV. This resolution is the best reported to date for hypernuclear reaction spectroscopy. The he 7 Lambda binding energy supplies the last missing information of the A=7, T=1 hypernuclear iso-triplet, providing a new input for the charge symmetry breaking (CSB) effect of \Lambda N potential.
The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles
G0 Collaboration,D. Androic,D. S. Armstrong,J. Arvieux,R. Asaturyan,T. D. Averett,S. L. Bailey,G. Batigne,D. H. Beck,E. J. Beise,J. Benesch,F. Benmokhtar,L. Bimbot,J. Birchall,A. Biselli,P. Bosted,H. Breuer,P. Brindza,C. L. Capuano,R. D. Carlini,R. Carr,N. Chant,Y. -C. Chao,R. Clark,A. Coppens,S. D. Covrig,A. Cowley,D. Dale,C. A. Davis,C. Ellis,W. R. Falk,H. Fenker,J. M. Finn,T. Forest,G. Franklin,R. Frascaria,C. Furget,D. Gaskell,M. T. W. Gericke,J. Grames,K. A. Griffioen,K. Grimm,G. Guillard,B. Guillon,H. Guler,K. Gustafsson,L. Hannelius,J. Hansknecht,R. D. Hasty,A. M. Hawthorne Allen,T. Horn,T. M. Ito,K. Johnston,M. Jones,P. Kammel,R. Kazimi,P. M. King,A. Kolarkar,E. Korkmaz,W. Korsch,S. Kox,J. Kuhn,J. Lachniet,R. Laszewski,L. Lee,J. Lenoble,E. Liatard,J. Liu,A. Lung,G. A. MacLachlan,J. Mammei,D. Marchand,J. W. Martin,D. J. Mack,K. W. McFarlane,D. W. McKee,R. D. McKeown,F. Merchez,M. Mihovilovic,A. Micherdzinska,H. Mkrtchyan,B. Moffit,M. Morlet,M. Muether,J. Musson,K. Nakahara,R. Neveling,S. Niccolai,D. Nilsson,S. Ong,S. A. Page,V. Papavassiliou,S. F. Pate,S. K. Phillips,P. Pillot,M. L. Pitt,M. Poelker,T. A. Porcelli,G. Quemener,B. P. Quinn,W. D. Ramsay,A. W. Rauf,J. -S. Real,T. Ries,J. Roche P. Roos,G. A. Rutledge,J. Schaub,J. Secrest,T. Seva,N. Simicevic,G. R. Smith,D. T. Spayde,S. Stepanyan,M. Stutzman,R. Suleiman,V. Tadevosyan,R. Tieulent,J. van de Wiele,W. T. H. van Oers,M. Versteegen,E. Voutier,W. F. Vulcan,S. P. Wells,G. Warren,S. E. Williamson,R. J. Woo,S. A. Wood
Physics , 2011, DOI: 10.1016/j.nima.2011.04.031
Abstract: In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. The overall design and performance of this experimental system is discussed.
Direct Measurements of the Lifetime of Heavy Hypernuclei
X. Qiu,L. Tang,A. Margaryan,P. Achenbach,A. Ahmidouch,I. Albayrak,D. Androic,A. Asaturyan,R. Asaturyan,O. Ates,R. Badui,P. Baturin,W. Boeglin,J. Bono,E. Brash,P. Carter,C. Chen,X. Chen,A. Chiba,E. Christy,M. M. Dalton,S. Danagoulian,R. De Leo,D. Doi,M. Elaasar,R. Ent,H. Fenker,Y. Fujii,M. Furic,M. Gabrielyan,L. Gan,F. Garibaldi,D. Gaskell,A. Gasparian,T. Gogami,O. Hashimoto,T. Horn,B. Hu,E. V. Hungerford,M. Jones,H. Kanda,M. Kaneta,M. Kawai,D. Kawama,H. Khanal,M. Kohl,A. Liyanage,W. Luo,K. Maeda,P. Markowitz,T. Maruta,A. Matsumura,V. Maxwell,A. Mkrtchyan,H. Mkrtchyan,S. Nagao,S. N. Nakamura,A. Narayan,C. Neville,G. Niculescu,M. I. Niculescu,A. Nunez,Nuruzzaman,Y. Okayasu,T. Petkovic,J. Pochodzalla,J. Reinhold,V. M. Rodriguez,C. Samanta,B. Sawatzky,T. Seva,A. Shichijo,V. Tadevosyan,N. Taniya,K. Tsukada,M. Veilleux,W. Vulcan,F. R. Wesselmann,S. A. Wood,L. Ya,T. Yamamoto,Z. Ye,K. Yokota,L. Yuan,S. Zhamkochyan,L. Zhu
Physics , 2012,
Abstract: The lifetime of a Lambda particle embedded in a nucleus (hypernucleus) decreases from that of free Lambda decay due to the opening of the Lambda N to NN weak decay channel. However, it is generally believed that the lifetime of a hypernucleus attains a constant value (saturation) for medium to heavy hypernuclear masses, yet this hypothesis has been difficult to verify. The present paper reports a direct measurement of the lifetime of medium-heavy hypernuclei produced with a photon-beam from Fe, Cu, Ag, and Bi targets. The recoiling hypernuclei were detected by a fission fragment detector using low-pressure multi-wire proportional chambers. The experiment agrees remarkably well with the only previously-measured single-species heavy-hypernucleus lifetime, that of Fe56_Lambda at KEK, and has significantly higher precision. The experiment disagrees with the measured lifetime of an unknown combination of heavy hypernuclei with 180
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