199683835
Energy Resolution and Rise Time of HPGe Detectors in High Magnetic Fields
120181374
The study of hypernuclei with heavy ion beams at GSI
The international HypHI collaboration is proposing a hypernuclear spectroscopy with stable heavy ion beams and rare isotope beams at GSI and FAIR in order to study neutron/proton rich hypernuclei and eventually to measure hypernuclear magnetic moments. As Phase 0 of the HypHI project, we propose the feasibility study of heavy ion induced hypernuclear spectroscopy by observing a mesonic weak decay from H Λ 3 , H Λ 4 and He Λ 5 with 6Li beams at 2 A GeV impinging on a 12C target. The physics motivations, experimental setup and the expected results will be discussed.
122641390
The T=2 mirrors 36Ca and 36S: A test for isospin symmetry of shell gaps at the driplines
The first excited 2 + state of 36 Ca has been identified by its γ -decay, exploiting the two-step fragmentation technique at the FRS-RISING setup at GSI. This is the heaviest Tz =− 2 nucleus in the Segre chart in which a γ -decay of an excited state has been observed. A stable beam of 40 Ca at 420A MeV impinged on a primary 9 Be target. Out of the secondary beam of fragmentation products, 37 Ca was separated by the FRS and struck on a second 9 Be target at the final focus of the FRS. The energy for the 2 + decay of 36 Ca was determined to be 3015(16) keV, which is 276 keV lower than in its T = 2 mirror 36 S. This mirror energy difference (MED) is discussed in the framework of shell model calculations using a 16 O core, the sd shell isospin symmetric interaction USD and experimental single-particle energies from 17 Oa nd 17 F. The results show that the MED within the sd shell provide a sensitive test for the evolution of the N , Z = 14, 16 subshell gaps towards the driplines. Especially the N, Z = 16 gap is determined by Thomas–Ehrman shift in the A = 17, T = 1/2 isospin doublet, while Coulomb effects are found to have marginal influence. © 2007 Elsevier B.V. All rights reserved.
53994621
RISING: Gamma‐ray Spectroscopy with Radioactive Beams at GSI
The Rare Isotope Spectroscopic INvestigation at GSI (RISING) project is a major pan‐European collaboration. Its physics aims are the studies of exotic nuclear matter with abnormal proton‐to‐neutron ratios compared with naturally occurring isotopes. RISING combines the FRagment Separator (FRS) which allows relativistic energies and projectile fragmentation reactions with EUROBALL Ge Cluster detectors for γ spectroscopic research. The RISING setup can be used in two different configurations. Either the nuclei of interest are investigated after being stopped or the heavy ions hit a secondary target at relativistic energies and the thereby occurring excitations are studied. For the latter case, MINIBALL Ge detectors and the HECTOR array are used in addition. Example achievements of the Fast Beam setup are presented and compared to various shell model calculations, while for the Stopped Beam setup initial results are shown.
9594769
108Sn Studied with Intermediate-energy Coulomb Excitation
The unstable neutron-deficient Sn-108 isotope has been studied in inverse kinematics by intermediate-energy Coulomb excitation using the RISING/FRS experimental setup at GSI. This is the highest Z nucleus studied so far with this method. Its reduced transition probability B (E2;0(g.s.)(+)-> 2(1)(+)) has been measured for the first time. The extracted B(E2) value of 0.230(57)e(2) b(2) has been determined relative to the known value in the stable Sn-112 isotope. The result is discussed in the framework of recent large-scale shell model calculations performed with realistic effective interactions. The roles of particle-hole excitations of the Sn-100 core and of the Z=50 shell gap for the E2 polarization are investigated.
9105602
Charged superstrings in background gauge fields and spectrum-generating algebra
The spectrum-generating algebra (SGA) for charged superstrings placed in constant background magnetic fields is constructed. Contrary to the neutral string this algebra is characteristic of including the cyclotron frequency. The Regge intercept and superconformal anomalies are calculated to be shifted by the cyclotron frequency and Dbrane parameters from the conventional values.
118968133
Charged Strings and Spectrum-Generating Algebra
We consider a system that both ends of a charged open string are attached on the D$p$-brane with constant electromagnetic fields. Contrary to neutral strings, the quantization of charged strings has not been so far considered well. For this system we construct the spectrum-generating algebra (SGA), which involves the cyclotron frequency. When the cyclotron frequency is set to be zero, the SGA is reduced to the ordinary SGA for neutral strings. The new SGA for charged strings guarantees that this system is ghost-free if certain conditions are satisfied. We also consider its application to the Hall effect for charged strings.
15820997
Geodesic flows for the Neumann-Rosochatius systems
The Relationship between the Neumann system and the Jacobi system in arbitrary dimensions is elucidated from the point of view of constrained Hamiltonian systems. Dirac brackets for canonical variables of both systems are derived from the constrained Hamiltonians. The geodesic equations corresponding to the Rosochatius system are studied as an application of our method. As a consequence a new class of nonlinear integrable equations is derived along with their conserved quantities.
123654851
KN Algebra Derived from Virasoro Algebra with Vertex Operators
Recently there have been several intensive attempts to study conformal field theories over a higher-genus Riemann surface r by means of operator formalisms. )-7) More recently Krichever and N ovikov have introduced a new kind of algebra (KN algebra) onto r as a natural extension of the Virasoro algebra.),9) This KN algebra contains also a subspace responsible for the Teichmliller deformations (see footnote on p. 166). In a series of papers)-14) Bonora et al. have applied the KN formalism to construct the BRST charge, Kac-Moody algebra, a global operator formalism for be systems and so on. Other contributions on this line can be found in Refs. 15)~20). In this paper we consider a system in which external fields such as tachyon field, symmetric and antisymmetric massless tensor fields are interacting with the closed bosonic string. By using the Virasoro algebra for such an interacting string we derive the corresponding KN algebra with vertex operators. We make use of the holomorphic property of integrand in the KN generator L i . This property allows us to relate the KN generator with the Virasoro generator. ) The Virasoro algebra with vertex operators is known to hold only when the mass of tachyon is a' m=-4 and external massless tensor fields satisfy the Lorentz condition.) Then such a derivation becomes possible. In § 2 we summarize the KN bases. In § 3 the KN algebra with vertex operators is derived from the Virasoro algebra with vertex operators. In § 4 we consider the same problem for the ghost b-e system. The final section is devoted to concluding remarks.
78088700
Dual Models of Weak Interactions of Leptons and Quarks
Composite models of leptons and quarks have heen considered on a hypothesis of lepton­ quark symmetry. This hypothesis leads us to the dual models of weak interactions of leptons and quarks. Some experimental tests to the weak duality in high energy lepton reaction will be proposed.