共查询到20条相似文献,搜索用时 31 毫秒
1.
Petri M Fallon P Macchiavelli AO Paschalis S Starosta K Baugher T Bazin D Cartegni L Clark RM Crawford HL Cromaz M Dewald A Gade A Grinyer GF Gros S Hackstein M Jeppesen HB Lee IY McDaniel S Miller D Rajabali MM Ratkiewicz A Rother W Voss P Walsh KA Weisshaar D Wiedeking M Brown BA 《Physical review letters》2011,107(10):102501
Establishing how and when large N/Z values require modified or new theoretical tools is a major quest in nuclear physics. Here we report the first measurement of the lifetime of the 2(1)+ state in the near-dripline nucleus 20C. The deduced value of τ(2(1)+)=9.8±2.8(stat)(-1.1)(+0.5)(syst) ps gives a reduced transition probability of B(E2; 2(1)+→0(g.s.)+)=7.5(-1.7)(+3.0)(stat)(-0.4)(+1.0)(syst) e2 fm4 in good agreement with a shell model calculation using isospin-dependent effective charges. 相似文献
2.
Van de Walle J Aksouh F Ames F Behrens T Bildstein V Blazhev A Cederkäll J Clément E Cocolios TE Davinson T Delahaye P Eberth J Ekström A Fedorov DV Fedosseev VN Fraile LM Franchoo S Gernhauser R Georgiev G Habs D Heyde K Huber G Huyse M Ibrahim F Ivanov O Iwanicki J Jolie J Kester O Köster U Kröll T Krücken R Lauer M Lisetskiy AF Lutter R Marsh BA Mayet P Niedermaier O Nilsson T Pantea M Perru O Raabe R Reiter P Sawicka M Scheit H Schrieder G Schwalm D Seliverstov MD Sieber T Sletten G 《Physical review letters》2007,99(14):142501
Neutron-rich, radioactive Zn isotopes were investigated at the Radioactive Ion Beam facility REX-ISOLDE (CERN) using low-energy Coulomb excitation. The energy of the 2(1)+ state in 78Zn could be firmly established and for the first time the 2+ --> 0(1)+ transition in 80Zn was observed at 1492(1) keV. B(E2,2(1)+ --> 0(1)+) values were extracted for (74,76,78,80)Zn and compared to large scale shell model calculations. With only two protons outside the Z=28 proton core, 80Zn is the lightest N=50 isotone for which spectroscopic information has been obtained to date. Two sets of advanced shell model calculations reproduce the observed B(E2) systematics. The results for N=50 isotones indicate a good N=50 shell closure and a strong Z=28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus 78Ni. 相似文献
3.
Drutskoy A Abe K Abe K Adachi I Aihara H Akatsu M Asano Y Aushev T Bahinipati S Bakich AM Bay A Bedny I Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Brodzicka J Browder TE Chang P Chao Y Chen A Chen KF Chen WT Cheon BG Chistov R Choi SK Choi Y Chuvikov A Cole S Dalseno J Danilov M Dash M Eidelman S Eiges V Enari Y Fang F Fratina S Gabyshev N Gershon T Go A Gokhroo G Golob B Hayasaka K Hayashii H Hazumi M Higuchi T Hinz L Hokuue T Hoshi Y Hou S Hou WS Imoto A Inami K Ishikawa A Iwasaki M 《Physical review letters》2005,94(6):061802
The decays B0-->D+sJK- and B0-->D-sJpi+ are studied for the first time. A significant signal is observed in the B0-->D*sJ(2317)+K- decay channel with B(B0-->D*sJ(2317)+K-) x B(D*sJ(2317)+-->D+spi0)=(5.3(+1.5)(-1.3)+/-0.7+/-1.4) x 10(-5). No signals are observed in the B0-->D*sJ(2317)-pi+, B0-->DsJ(2460)+K-, and B 0-->DsJ(2460)-pi+ decay modes, and upper limits are obtained. The analysis is based on a data set of 140 fb(-1) collected by the Belle experiment at the asymmetric e+e- collider KEKB. 相似文献
4.
Vaman C Andreoiu C Bazin D Becerril A Brown BA Campbell CM Chester A Cook JM Dinca DC Gade A Galaviz D Glasmacher T Hjorth-Jensen M Horoi M Miller D Moeller V Mueller WF Schiller A Starosta K Stolz A Terry JR Volya A Zelevinsky V Zwahlen H 《Physical review letters》2007,99(16):162501
Rare isotope beams of neutron-deficient 106,108,110Sn from the fragmentation of 124Xe were employed in an intermediate-energy Coulomb excitation experiment. The measured B(E2,0(1)(+)-->2(1)(+)) values for 108Sn and 110Sn and the results obtained for the 106Sn show that the transition strengths for these nuclei are larger than predicted by current state-of-the-art shell-model calculations. This discrepancy might be explained by contributions of the protons from within the Z = 50 shell to the structure of low-energy excited states in this region. 相似文献
5.
Trischuk W de Troconiz JF Truitt S Tseng J Turini N Ukegawa F Valls J Vejcik S Velev G Vidal R Vilar R Vologouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ Watanabe T Waters D Watts T Webb R Wenzel H 《Physical review letters》2000,84(5):835-840
We present the results of a search for pair production of a fourth-generation charge -1 / 3 quark (b(')) in sqrt[s] = 1.8 TeV p&pmacr; collisions using 88 pb(-1) of data obtained with the Collider Detector at Fermilab. We assume that both quarks decay via the flavor-changing neutral current process b(')-->bZ(0) and that the b(') mass is greater than m(Z)+m(b). We studied the decay mode b(')b(');-->Z(0)Z(0)b&bmacr; where one Z0 decays into e(+)e(-) or &mgr;(+)&mgr;(-) and the other decays hadronically, giving a signature of two leptons plus jets. An upper limit on the sigma(p&pmacr;-->b(')b(');)x[B(b(')-->bZ(0))](2) is established as a function of the b(') mass. We exclude at 95% confidence level a b(') quark with mass between 100 and 199 GeV/c(2) for B(b(')-->bZ(0)) = 100%. 相似文献
6.
Using coaxial impact collision ion scattering spectroscopy, we have investigated Sn thin film growth on Si(1 1 1)√3×√3-Sn and hydrogen-terminated Si(1 1 1) surfaces at room temperature. Sn formed crystalline film with β-Sn structure on Si(1 1 1)√3×√3-Sn surface, but on the hydrogen-terminated Si(1 1 1) surface, the epitaxial growth of Sn thin film was disrupted, and Sn grew as a polycrystalline film. The growth orientational relationship of the Sn film grown on Si(1 1 1)√3×√3-Sn surface was found to be . In the works, we found that interface structure plays a decisive role for the growth mode, crystallinity, and growth orientation of the growth of thin film. 相似文献
7.
Abulencia A Acosta D Adelman J Affolder T Akimoto T Albrow MG Ambrose D Amerio S Amidei D Anastassov A Anikeev K Annovi A Antos J Aoki M Apollinari G Arguin JF Arisawa T Artikov A Ashmanskas W Attal A Azfar F Azzi-Bacchetta P Azzurri P Bacchetta N Bachocou H Badgett W Barbaro-Galtieri A Barnes VE Barnett BA Baroiant S Bartsch V Bauer G Bedeschi F Behari S Belforte S Bellettini G Bellinger J Belloni A Ben-Haim E Benjamin D Beretvas A Beringer J Berry T Bhatti A Binkley M Bisello D Bishai M 《Physical review letters》2006,96(8):082002
We report the first evidence for a fully reconstructed decay mode of the B(c)+- meson in the channel B(c)+- --> J/psi pi+-, with J/psi --> mu+ mu-. The analysis is based on an integrated luminosity of 360 pb(-1) in pp collisions at 1.96 TeV center of mass energy collected by the Collider Detector at Fermilab. We observe 14.6 +/- 4.6 signal events with a background of 7.1 +/- 0.9 events, and a fit to the J/psi pi+-mass spectrum yields a B(c)+- mass of 6285.7 +/- 5.3(stat) +/- 1.2(syst) MeV/c2. The probability of a peak of this magnitude occurring by random fluctuation in the search region is estimated as 0.012%. 相似文献
8.
Link JM Yager PM Anjos JC Bediaga I Castromonte C Machado AA Magnin J Massafferi A de Miranda JM Pepe IM Polycarpo E dos Reis AC Carrillo S Casimiro E Cuautle E Sánchez-Hernández A Uribe C Vázquez F Agostino L Cinquini L Cumalat JP O'Reilly B Segoni I Stenson K Butler JN Cheung HW Chiodini G Gaines I Garbincius PH Garren LA Gottschalk E Kasper PH Kreymer AE Kutschke R Wang M Benussi L Bertani M Bianco S Fabbri FL Pacetti S Zallo A Reyes M Cawlfield C Kim DY Rahimi A Wiss J Gardner R Kryemadhi A 《Physical review letters》2005,95(5):052003
A high statistics measurement of the D(s)+ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis of the two decay modes, D(s)+ --> phi(1020)pi+ and D(s)+ -->K*(892)0K+, used for the measurement. The measured lifetime is 507.4 +/- 5.5(stat) +/- 5.1(syst) fs using 8961 +/- 105 D(s)+ --> phi(1020)pi+ and 4680 +/- 90 D(s)+ --> K*(892)0K+ decays. This is a significant improvement over the present world average. 相似文献
9.
Yang H Nakao M Abe K Abe K Aihara H Asano Y Aushev T Bahinipati S Bakich AM Ban Y Bedny I Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Brodzicka J Browder TE Chang MC Chang P Chao Y Chen A Chen WT Cheon BG Chistov R Choi SK Choi Y Choi YK Chuvikov A Cole S Dalseno J Dash M Eidelman S Enari Y Fang F Gabyshev N Garmash A Gershon T Gokhroo G Golob B Haba J Hayasaka K Hayashii H Hazumi M Hinz L Hokuue T Hoshi Y Hsiung YB Iijima T Imoto A Inami K Iwasaki Y Kang JH Kang JS Kataoka SU 《Physical review letters》2005,94(11):111802
We report the observation of the radiative decay B+-->K1(1270)(+) gamma using a data sample of 140 fb(-1) taken at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- collider. We find the branching fraction to be B(B+-->K1(1270)(+)gamma)=(4.3+/-0.9(stat.)+/-0.9(syst.))x10(-5) with a significance of 7.3sigma. We find no significant signal for B+-->K1(1400)(+)gamma and set an upper limit B(B+-->K1(1400)(+)gamma)<1.5 x 10(-5) at the 90% confidence level. We also measure inclusive branching fractions for B+-->K+pi+pi-gamma and B0-->K0pi+pi-gamma in the mass range 1 GeV/c(2)相似文献
10.
O(1D)+N2O→NO+NO反应的理论研究 总被引:3,自引:3,他引:0
应用三体模型及扩展的LEPS势能面(PES),对初始条件为(Ecol=55 kJ/mol,v=0,j=0)的O(1D)+N2O→NO+NO反应体系进行了准经典轨线(QCT)计算.根据计算结果对体系的势能面及反应机理进行详细的分析和讨论,较全面地研究了此反应体系的动力学特征. 相似文献
11.
The B 1pi(u) electronic state of Na2 was excited by the 441.6 nm He-Cd laser line. The Na atomic transitions and the A 1sigma(u)+ --> X 1sigma(g)+ band of Na2 were recorded. From the intensities and spectra of the Na and Na2 fluorescence several collisional processes in the excited sodium atom-dimer system were identified. The Na atomic lines are the result of collisional energy transfer from Na2 (B 1pi(u)) to Na(3P). Predissociation process may also contribute to atomic fluorescence. The A 1sigma(u)+ --> X 1sigma(g)+ band is interpreted through a populating mechanism involving collisional transfer from B 1pi(u) to 2 1sigma(g)+ followed by a radiative transfer to the A 1sigma(u)+ state. From the decay constants and fluorescence intensities, the rate coefficient at 360 degrees C for collisional energy transfer from Na2 (B 1pi(u)) to Na2 (2 1sigma(g)+) was found to be 5.7 x 10(-10) cm3 x s(-1). The predissociation rate of the B 1pi(u) is 2.7 x 10(6) s(-1). 相似文献
12.
The adsorption of NO on Pt(111), and the (2 × 2)Sn/Pt(111) and (√3 × √3)R30°Sn/Pt(111) surface alloys has been studied using LEED, TPD and HREELS. NO adsorption produces a (2 × 2) LEED pattern on Pt(111) and a (2√3 × 2√3)R30° LEED pattern on the (2 × 2)Sn/Pt(111) surface. The initial sticking coefficient of NO on the (2 × 2)Sn/Pt(111) surface alloy at 100 K is the same as that on Pt(111), S0 = 0.9, while the initial sticking coefficient of NO on the (√3 × √3)R30°Sn/Pt(111) surface decreases to 0.6. The presence of Sn in the surface layer of Pt(111) strongly reduces the binding energy of NO in contrast to the minor effect it has on CO. The binding energy of β-state NO is reduced by 8–10 kcal/mol on the Sn/Pt(111) surface alloys compared to Pt(111). HREELS data for saturation NO coverage on both surface alloys show two vibrational frequencies at 285 and 478 cm−1 in the low frequency range and only one N-O stretching frequency at 1698 cm−1. We assign this NO species as atop, bent-bonded NO. At small NO coverage, a species with a loss at 1455 cm−1 was also observed on the (2 × 2)Sn/ Pt(111) surface alloy, similar to that observed on the Pt(111) surface. However, the atop, bent-bonded NO is the only species observed on the (√3 × √3)R30°Sn/Pt(111) surface alloy at any NO coverage studied. 相似文献
13.
Suzuki K Fujita M Geissel H Gilg H Gillitzer A Hayano RS Hirenzaki S Itahashi K Iwasaki M Kienle P Matos M Münzenberg G Ohtsubo T Sato M Shindo M Suzuki T Weick H Winkler M Yamazaki T Yoneyama T 《Physical review letters》2004,92(7):072302
Deeply bound 1s states of pi(-) in (115,119,123)Sn were preferentially observed using the Sn(d,3He) pion-transfer reaction under the recoil-free condition. The 1s binding energies and widths were precisely determined and were used to deduce the isovector parameter of the s-wave pion-nucleus potential to be b1=-(0.115+/-0.007)m(-1)(pi). The observed enhancement of |b(1)| over the free piN value (b(free)1/b1=0.78+/-0.05) indicates a reduction of the chiral order parameter, f*pi(rho)2/f2pi approximately 0.64, at the normal nuclear density, rho=rho(0). 相似文献
14.
N.-G. Jonsson A. Bäcklin J. Kantele R. Julin M. Luontama A. Passoja 《Nuclear Physics A》1981,371(2):333-348
0+, 2+, 44 and 3? states in 112–124Sn have been studied with the (p, p′γ) reaction and in Coulomb excitation. Absolute E2 transition rates between these levels have been extracted with the aid of the Winther-de Boer code. For 116,118Sn, B(E2; 41+ → 21+) ≈ 20 W.u., suggesting a two-phonon character of the 41+ states. For the lighter and heavier isotopes, this value is significantly smaller. All observed values of B(E2; 22+ → 21+) and B(E2; 23+→ 21+) are about 5 W.u. Also. values of B(E3; 01+ → 3?1) have been measured for all stable even Sn nuclei. In 116Sn the branching ratio (31? → 01+)/(31? → 21+) has been measured. From this we obtain a half-life of 0.34±0.07 ps for the first 3? level in 116Sn and B(E1; 31? → 21+) = (1.4±0.3) × 10?5'e2 · b, corresponding to a hindrance factor of 103. 相似文献
15.
Alexander JP Baker R Bebek C Berger BE Berkelman K Blanc F Boisvert V Cassel DG Dickson M Drell PS Ecklund KM Ehrlich R Foland AD Gaidarev P Gibbons L Gittelman B Gray SW Hartill DL Heltsley BK Hopman PI Jones CD Kreinick DL Lohner M Magerkurth A Meyer TO Mistry NB Nordberg E Patterson JR Peterson D Riley D Thayer JG Thies PG Valant-Spaight B Warburton A Avery P Prescott C Rubiera AI Yelton J Zheng J Brandenburg G Ershov A Gao YS Kim DY Wilson R Browder TE Li Y Rodriguez JL Yamamoto H 《Physical review letters》2001,86(13):2737-2741
We analyze 9.7x10(6) B_B pairs recorded with the CLEO detector to determine the production ratio of charged to neutral B-meson pairs produced at the Upsilon(4S) resonance. We measure the rates for B0-->J/psiK((*)0) and B+-->J/psiK((*)+) decays and use the world-average B-meson lifetime ratio to extract the relative widths f(+-) / f(00) = gamma(Upsilon(4S)-->B+B-) / gamma(Upsilon(4S)-->B0 B-0)) = 1.04+/-0.07(stat)+/-0.04(syst). With the assumption that f(+-)+f(00) = 1, we obtain f(00) = 0.49+/-0.02(stat)+/-0.01(syst) and f(+-) = 0.51+/-0.02(stat)+/-0.01(syst). This production ratio and its uncertainty apply to all exclusive B-meson branching fractions measured at the Upsilon(4S) resonance. 相似文献
16.
Artuso M Boulahouache C Blusk S Butt J Dambasuren E Dorjkhaidav O Li J Menaa N Mountain R Muramatsu H Nandakumar R Redjimi R Sia R Skwarnicki T Stone S Wang JC Zhang K Csorna SE Bonvicini G Cinabro D Dubrovin M Bornheim A Pappas SP Weinstein AJ Rosner JL Briere RA Chen GP Ferguson T Tatishvili G Vogel H Watkins ME Adam NE Alexander JP Berkelman K Cassel DG Crede V Duboscq JE Ecklund KM Ehrlich R Fields L Galik RS Gibbons L Gittelman B Gray R Gray SW Hartill DL Heltsley BK Hertz D Hsu L Jones CD 《Physical review letters》2005,94(3):032001
We have studied the inclusive photon spectra in Upsilon(2S) and Upsilon(3S) decays using a large statistics data sample obtained with the CLEO III detector. We present the most precise measurements of electric dipole (E1) photon transition rates and photon energies for Upsilon(2S) --> gammachi(bJ)(1P) and Upsilon(3S) --> gammachi(bJ)(2P) (J = 0, 1, 2). We measure the rate for a rare E1 transition Upsilon(3S) --> gammachi(b0)(1P) for the first time. We also set upper limits on the rates for the hindered magnetic dipole (M1) transitions to the eta(b)(1S) and eta(b)(2S) states. 相似文献
17.
Tajima O Hazumi M Adachi I Aihara H Aulchenko V Aushev T Bakich AM Barberio E Bay A Bedny I Bhardwaj V Bitenc U Bozek A Bracko M Browder TE Chang MC Chang P Chen A Chen KF Chen WT Cheon BG Chiang CC Chistov R Cho IS Choi Y Choi YK Dalseno J Danilov M Dash M Drutskoy A Eidelman S Epifanov D Go A Gokhroo G Golob B Haba J Hayasaka K Hayashii H Heffernan D Hokuue T Hoshi Y Hou WS Hsiung YB Hyun HJ Iijima T Ikado K Inami K Ishikawa A Ishino H Itoh R Iwasaki M Iwasaki Y Joshi NJ Kah DH Kaji H Kang JH 《Physical review letters》2007,99(21):211601
We report the first search for CP-violating decays of the Upsilon(4S) using a data sample that contains 535 x 10(6) Upsilon(4S) mesons with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. A partial reconstruction technique is employed to enhance the signal sensitivity. No significant signals were observed. We obtain an upper limit of 4 x 10(-7) at the 90% confidence level for the branching fractions of the CP violating modes, Upsilon(4S)-->B(0)B(0)-->J/psiK(S)(0)+J/psi(eta(c))K(S)(0). Extrapolating the result, we find that an observation with 5sigma significance is expected with a 30 ab(-1) data sample, which is within the reach of a future super B factory. 相似文献
18.
Padilla-Rodal E Galindo-Uribarri A Baktash C Batchelder JC Beene JR Bijker R Brown BA Castaños O Fuentes B del Campo JG Hausladen PA Larochelle Y Lisetskiy AF Mueller PE Radford DC Stracener DW Urrego JP Varner RL Yu CH 《Physical review letters》2005,94(12):122501
The B(E2;0(+)(1)-->2(+)(1)) values for the radioactive neutron-rich germanium isotopes (78,80)Ge and the closed neutron shell nucleus 82Ge were measured at the HRIBF using Coulomb excitation in inverse kinematics. These data allow a study of the systematic trend between the subshell closures at N=40 and 50. The B(E2) behavior approaching N=50 is similar to the trend observed for heavier isotopic chains. A comparison of the experimental results with a shell model calculation demonstrates persistence of the N=50 shell gap and a strong sensitivity of the B(E2) values to the effective interaction. 相似文献
19.
Abe K Abe K Abe R Adachi I Ahn BS Aihara H Akatsu M Asano Y Aso T Aulchenko V Aushev T Bakich AM Banas E Behari S Behera PK Bondar A Bozek A Browder TE Casey BC Chang P Chao Y Chen KF Cheon BG Chistov R Choi SK Choi Y Dong LY Dragic J Drutskoy A Eidelman S Enari Y Fang F Fujii H Fukushima M Gabyshev N Garmash A Gershon T Gordon A Gotow K Guo R Haba J Hamasaki H Handa F Hara K Hara T Hastings NC Hayashii H Hazumi M Heenan EM Higuchi I Higuchi T Hirano H Hojo T Hokuue T Hoshina K Hou SR Hou WS 《Physical review letters》2002,88(5):052002
We report the first observation of color-suppressed B( 0)-->D(0)pi(0), D(*0)pi(0), D0eta, and D0omega decays, and evidence for B( 0)-->D(*0)eta and D(*0)omega. The branching fractions are B(B( 0)-->D0pi(0)) = (3.1 +/- 0.4 +/- 0.5)x10(-4), B(B( 0) -->D(*0)pi(0)) = (2.7(+0.8+0.5)(-0.7-0.6))x10(-4), B(B( 0) --> D0eta) = (1.4(+0.5)(-0.4) +/- 0.3)x10(-4), B(B( 0) --> D0omega) = (1.8 +/- 0.5(+0.4)(-0.3))x10(-4), and we set 90% confidence level upper limits of B(B( 0) --> D(*0)eta)<4.6 x 10(-4) and B(B( 0)-->D(*0)omega)<7.9 x 10(-4). The analysis is based on a data sample of 21.3 fb(-1) collected at the Upsilon(4S) resonance by the Belle detector at the KEKB e(+)e(-) collider. 相似文献
20.
We studied the atomic arrangements and the phase diagram of two-dimensional (2D) Bi–Sn binary films on Rh(111) with low-energy electron diffraction and scanning tunneling microscopy (STM). The 2D binary films exhibited (“2” × √3)-(Bi,Sn), (√7 × √7)R19°-(Bi,Sn), and (7 × 3√3)-(Bi,Sn) structures, depending on the compositional ratio of Bi and Sn. Atomically resolved STM images revealed that the binary films formed a BiSn3 ordered alloy for the (√7 × √7)R19°-(Bi,Sn) structure and a solid solution alloy for the (“2” × √3)-(Bi,Sn) structure. The atomic configuration for the (7 × 3√3)-(Bi,Sn) structure was closely related to that of (√7 × √7) R19°-(Bi,Sn). 相似文献