125 research outputs found

    Half-life of the I Π = 4 - intruder state in 34 P: M 2 transition strengths approaching the island of inversion

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    The half-life of the 2305-keV, I?=4 (-) intruder state in 34P has been measured as t 1/2=2.0(1) ns using ?-ray coincidence, fast-timing techniques with the Bucharest HPGe and LaBr 3:Ce detector array. Excited states in 34P were populated using the 18O (18O,pn )34P fusion-evaporation reaction at a beam energy of 36 MeV. Reduced transition probabilities have been calculated for different values of the M2/E3 mixing ratio, ? E3/M2, and compared with shell-model estimates. For small values of the mixing ratio, the B(M2) value was found to be consistent with similar transitions associated with the occupation of neutron f 7/2 configurations in this mass region. � 2012 American Physical Society

    Comparative Studies of Muckraking in US and in China

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    无论是一百多年前美国经历的“镀金时代”,还是中国现在的“GDP时代”,两国在迎来经济腾飞的同时,也面临着前所未有的社会问题与矛盾。不同的政治、经济、文化体制,为何有着相似的社会转型?究其根本:在财富积累过程中,人们的观念以物质利益为重,适合于新社会的道德观念,社会制度没有建立,一部分人私欲无法得到抑制,因此产生坑蒙拐骗、贪污腐化等“粪”、“黑”现象,需要被“扒”和被“揭”。本文以拉斯韦尔的5W模式作为维度对先后发生在两国的“扒粪运动”和“揭黑运动”进行对比研究,试图了解二者的异同,并尝试探讨在中国现有的传播体制下,媒体应如何形成与国家、社会的良性互动,传递负责人的批判的声音,维系民主与法制。 ...During both Gilded Age the United States experienced a hundred years ago, and GDP Era China is now experiencing, two countries ushered in the rapid economic growth, but also faced with unprecedented social problems and contradictions. Controlled by different political, economic and cultural system, why do we have a similar social transformation? The essence is the same: in the wealth accumulation...学位:文学硕士院系专业:新闻传播学院广告学系_传播学学号:3192008115309

    β-Delayed and isomer spectroscopy of neutron-rich Ta and W isotopes

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    Decays of neutron-rich A ~ 190 nuclei have been studied following projectile fragmentation of a 208Pb beam on a 9Be target at the GSI Fragment Separator. Gamma-ray decays from previously reported isomeric states in 188Ta, 190W and 192, 193Re were used as internal calibrations for the particle identification analysis, together with the identification of previously unreported isomeric decays in 189Ta and 191W. The current work also identifies β-delayed γ rays following the decay of 188Ta to 188W for the first time.Algora, Alejandro, [email protected] ; Molina Palacios, Francisco Manuel, [email protected]; Rubio Barroso, Berta, [email protected]

    Search for lepton-number violating B+ -> X(-)l(+)l '(+) decays

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    We report on a search for eleven lepton-number violating processes B+ -> X(-)l(+)l'(+) with X- = K-, pi(-), rho(-), K*(-), or D- and l(+)/l'(+) = e(+) or 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 any of these modes and place 90% confidence level upper limits on their branching fractions in the range (1.5-26) x 10(-7)

    Lifetime measurement of neutron-rich even-even molybdenum isotopes

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    Background: In the neutron-rich A approximate to 100 mass region, rapid shape changes as a function of nucleon number as well as coexistence of prolate, oblate, and triaxial shapes are predicted by various theoretical models. Lifetime measurements of excited levels in the molybdenum isotopes allow the determination of transitional quadrupole moments, which in turn provides structural information regarding the predicted shape change. Purpose: The present paper reports on the experimental setup, the method that allowed one to measure the lifetimes of excited states in even-even molybdenum isotopes from mass A = 100 up to mass A = 108, and the results that were obtained. Method: The isotopes of interest were populated by secondary knock-out reaction of neutron-rich nuclei separated and identified by the GSI fragment separator at relativistic beam energies and detected by the sensitive PreSPEC-AGATA experimental setup. The latter included the Lund-York-Cologne calorimeter for identification, tracking, and velocity measurement of ejectiles, and AGATA, an array of position sensitive segmented HPGe detectors, used to determine the interaction positions of the gamma ray enabling a precise Doppler correction. The lifetimes were determined with a relativistic version of the Doppler-shift-attenuation method using the systematic shift of the energy after Doppler correction of a gamma-ray transition with a known energy. This relativistic Doppler-shift-attenuation method allowed the determination of mean lifetimes from 2 to 250 ps. Results: Even-even molybdenum isotopes from mass A = 100 to A = 108 were studied. The decays of the low-lying states in the ground-state band were observed. In particular, two mean lifetimes were measured for the first time: tau = 29.7(-9.1)(+11.3) ps for the 4(+) state of Mo-108 and tau = 3.2(-0.7)(+ 0.7) ps for the 6(+) state of Mo-102. Conclusions: The reduced transition strengths B(E2), calculated from lifetimes measured in this experiment, compared to beyond-mean-field calculations, indicate a gradual shape transition in the chain of molybdenum isotopes when going from A = 100 to A = 108 with a maximum reached at N = 64. The transition probabilities decrease for Mo-108 which may be related to its well-pronounced triaxial shape indicated by the calculations
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