122994285
TPC for investigation of double beta decaying nuclei in solid samples
A design of a large volume time projection chamber (TPC) for double beta decay measurements with solid samples is presented. The total surface of measured samples can be up to 2.5 m2. The chamber will operate in a magnetic field up to 0.07 T. The expected spatial resolution is better than 1 mm in electron drift direction and about 2 mm along the sense wires. The momentum resolution of about 10% should be reached. The background of the TPC will be very effectively suppressed by the visualization of each event. The TPC operating in an underground laboratory should reach a limit on the half-life of neutrinoless double beta decay of 1024 years.
121806959
Measurements of interaction cross sections for light neutron-rich nuclei at relativistic energies and determination of effective matter radii
Abstract We measured the interaction cross sections ( σ I ) of 10,11B, 12–20C, 14–23N, 16–24O and 18–26F on carbon targets at energies of around 950 A MeV. We then deduced the effective matter radii of the nuclei by a Glauber-model analysis. Based on the assumption of a core plus a valence neutron structure, we applied a Glauber-model analysis for a few-body system adapted for nuclei with an odd neutron number. We also deduced the effective nucleus-matter densities as well as some spectroscopic information for selected nuclei. Evidence for a one-neutron halo structure was found for 22N, 23O and 24F, as well as 19C.
119975957
The new element 112
The new element 112 was produced and identified unambiguously in an experiment at SHIP, GSI Darmstadt. Two decay chains of the isotope277112 were observed in irradiations of208Pb targets with70Zn projectiles of 344 MeV kinetic energy. The isotope decays by emission of α particles with a half-life of (240−90+430)µs. Two different α energies of (11,649±20) keV and (11,454±20) keV were measured for the two observed decays. The cross-section measured in three weeks of irradiations is (1.0−0.4+1.8) pb.
28960903
One-neutron removal measurement reveals 24O as a new doubly magic nucleus.
The first measurement of the momentum distribution for one-neutron removal from (24)O at 920A MeV performed at GSI, Darmstadt is reported. The observed distribution has a width (FWHM) of 99 +/- 4 MeV/c in the projectile rest frame and a one-neutron removal cross section of 63 +/- 7 mb. The results are well explained with a nearly pure 2s_{1/2} neutron spectroscopic factor of 1.74 +/- 0.19 within the eikonal model. This large s-wave probability shows a spherical shell closure thereby confirming earlier suggestions that (24)O is a new doubly magic nucleus.
122883967
Structure of neutron-rich oxygen isotopes
One-nucleon removal reactions at relativistic energies have been used as a spectroscopic tool for obtaining information about the ground state of neutron-rich oxygen isotopes. Using the FRS at GSI, the longitudinal momentum distributions of the emerging fragments after breakup were measured along with the one-nucleon removal cross-sections. The relative contributions of the remaining fragments in their ground and excited states have been determined for a few cases from measurements of γ rays in coincidence with the longitudinal momentum distribution. The controversial case of 23O has been directly addressed. Comparison of our exclusive momentum distributions for the one-neutron removal channel to theoretical momentum distributions calculated with an Eikonal model for the knockout process rendered a spin and parity of Iπ = 1/2+ for the 23O ground state. This result resolves the existent experimental discrepancy and supports sub-shell closure at N = 14 with a fairly pure 2s1/2 neutron in 23O.
8239147
New isomers in the full seniority scheme of neutron-rich lead isotopes: the role of effective three-body forces.
The neutron-rich lead isotopes, up to (216)Pb, have been studied for the first time, exploiting the fragmentation of a primary uranium beam at the FRS-RISING setup at GSI. The observed isomeric states exhibit electromagnetic transition strengths which deviate from state-of-the-art shell-model calculations. It is shown that their complete description demands the introduction of effective three-body interactions and two-body transition operators in the conventional neutron valence space beyond (208)Pb.
16527950
Backreaction and the rolling tachyon: an effective action point of view
Abstract We compute the decay of an unstable D9 brane in type IIA string theory including backreaction effects using an effective field theory approach. The open string tachyon on the brane is coupled consistently to the spacetime metric, the dilaton and the RR 9-form. The purpose of this note is to address the fate of the open string energy density, which remains constant if no interaction with the closed string modes is included. Our computations show that taking only into account the coupling to the massless closed strings the total energy stored in the open string sector vanishes asymptotically, independently how small one chooses g s . We find also the large time behaviour of the fields in the Einstein and string frames.
18587471
Gauge Theory Scattering from the AdS/CFT Correspondence
We use the AdS/CFT correspondence to study near forward scattering of colourless objects in gauge theory in the high energy limit. We find an unexpected from the gauge theory perspective ‘gravity-like’ s 1 behaviour of the amplitudes coming from bulk graviton exchange.
2683278
The Lund model at nonzero impact parameter
Abstract We extend the formulation of the longitudinal (1+1)-dimensional Lund model to nonzero impact parameter using the minimal area assumption. Complete formulae for the string breaking probability and the momenta of the produced mesons are derived using the string worldsheet Minkowskian helicoid geometry. For strings stretched into the transverse dimension, we find probability distribution with slope linear in m T similar to the statistical models but without any thermalization assumptions.
85537482
Rapidity and transverse momentum distributions of heavy quarks produced by double pomeron exchange
AbstractRapidity and transverse momentum distributions of heavy quarks produced by double exchange of Donnachie-Landshoff pomeron are presented and discussed. In the limit of small transverse momentum of the pair, the cross-section is almost independent of the sum ofq and
$$\bar q$$
 rapidities, but does depend on the rapidity difference and (rather strongly) on the transverse momenta of the produced quarks.
16060423
SO(N) superpotential, Seiberg–Witten curves and loop equations
Abstract We consider the exact superpotential of N =1 super-Yang–Mills theory with gauge group SO ( N ) and arbitrary tree-level polynomial superpotential of one adjoint Higgs field. A field-theoretic derivation of the glueball superpotential is given, based on factorization of the N =2 Seiberg–Witten curve. Following the conjecture of Dijkgraaf and Vafa, the result is matched with the corresponding SO ( N ) matrix model prediction. The verification involves an explicit solution of the first non-trivial loop equation, relating the spherical free energy to that of the non-orientable surfaces with topology RP 2 .