Coulomb dissociation of N 20,21

Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N20,21 are reported. Relativistic N20,21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the N19(n,γ)N20 and N20(n,γ)N21 excitation functions and thermonuclear reaction rates have been determined. The N19(n,γ)N20 rate is up to a factor of 5 higher at

On-line diagnostic tool for measurement of the time delay between two ultrashort light pulses

Ultrafast accelerator-based sources combined with synchronized femtosecond lasers are currently being developed. The method described here is intended as a jitter monitor at such facilities. We report on the possibility of extracting a time-offset signal between two different synchronized ultrashort light pulses. The method is based on sum-frequency generation in a nonlinear crystal. Aiming at extracting the time-difference from visible pulsed radiation from an x-ray undulator and femtosecond laser pulses we are investigating the possibility of obtaining timing information when one of the two pulses is very weak (10(6) photons/pulse). This will enable on-line monitoring of the relative timing of an accelerator-based free-electron laser and a synchronized visible laser. The spatial position of the sum-frequency mixed region is registered using a position sensitive detector (PSD). We show that for an 80 fs light source the described electronic equipment is capable of delivering a signal proportional to the temporal shift of different ultrashort light pulses with an accuracy of approximately 30 fs in a time interval of several ps

Systematics in the light response of BGO, CsI(T1) and GSO(Ce) scintillators to charged particles

The light response of a BGO crystal has been measured for particles Z = 1-8, A = 1-16 in the energy range similar to2-60 A MeV. The reaction products are identified by a DeltaE(Si) - E(Sci/PD) telescope, The position of the jump in the value of the signal from the PD at the punch-through points is used to calibrate both the DeltaE(Si) and E(Sci/PD) scales in MeV. The dependence of the light output on the energy E, ion atomic number Z and mass A is parameterized by the power law relation, L(Z, A, E) = a(1)((Z, A))E(a2(Z, A)). The parameters a(1) and a(2) have a smooth dependence on Z for all three crystals. The mass dependence of a(1), a(2) is deduced as a simple analytical expression, The systematics of these parameters is presented for BGO, CsI(Tl) and GSO(Ce) scintillators as a function of Z, A. Calculations of the response function, based on the Murray-Mayer model provide an excellent description of the shape of L(Z, A, E) versus E dependence, but show some deviations in the individual ion normalization constant for the BGO and GSO(Ce) scintillators. (C) 2002 Elsevier Science B.V. All rights reserved

Probing the liquid-gas coexistence in p+Xe reactions from 200 to 1400 MeV

The nuclear equation of state (EOS) is probed from statistical parameters, determined in an excitation function experiment on p + Xe-nat reactions at 200-1400 MeV. Total charge (Z) distributions follow a cascade-[multi]fragmentation-evaporation (CFEM) model well. The caloric curve in regions supposedly dominated by fast processes is compatible with a pure statistical multifragmentation (SMM) process, where the temperature (T)-excitation energy (epsilon*) relation starts in the Fermi liquid phase and progresses into a liquid/gas coexistence region, where it remains up to 1400 MeV. A local peak in T at epsilon* = 2.1 MeV agrees with the idea of sudden fragmentation. (c) 2006 Elsevier B.V. All rights reserved

Isospin effects on particle emission time sequence in E/A = 61 MeV Ar-36 + Sn-112,124 reactions

The emission time sequence of neutrons, protons, and deuterons is deduced from velocity-gated two-particle correlation functions in E/A = 61 MeV 36Ar+112,124Sn reactions. A dependence of the emission sequence on the isospin of the emitting source is observed

Proton in-beam tests of the Lund (RB)-B-3 calorimeter prototype

A small-scale prototype of the CALIFA calorimeter, which is a subsystem of the R 3 B detector, has been constructed and tested using the 179 MeV proton beam at The Svedberg Laboratory, Uppsala, Sweden. The prototype consists of 15 Csl(Tl) elements with a size of 10 x 30 x 130 mm(3), assembled in a 3 x 5 array. Each crystal was individually tested using gamma-ray sources and the light output uniformity along the longitudinal axes was adjusted to better than 0.6%. An energy resolution of similar to 0.5% has been achieved with a technique consisting of non-uniform polishing/lapping of the crystal side facets. The performance of the prototype is evaluated using experimental data and GEANT4 simulations. Results from the experiment, including multiplicity and sum spectra, show good agreement with simulations. The quality requirements for Csl(Tl) elements for construction of a high precision calorimeter/spectrometer are summarized. (C) 2009 Elsevier B.V. All rights reserved

Particle emission time sequence in intermediate energy heavy ion reactions

The CHIC Collaboration has performed a series of simultaneous pp, np and nn fermion interferometry experiments in order to study the space-time evolution of the emission sources in intermediate energy heavy ion reactions. Furthermore, when correlations of non-identical particles are available, additional model independent information on the emission chronology of the particles is obtained. In this contribution, after reviewing the method to determine the order of emission of non-identical particles, we discuss the emission chronology of neutrons and protons from the E/A = 45 MeV Ni-58 + Al-27 reaction and from the E/A = 60 MeV Ar-36 + Al-27 reaction, shown here for the first time

CHICSi - a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. II. Detectors

We describe the detectors for identification of charged particles and fragments in CHICSi, a large solid angle multitelescope system mounted inside an ultra-high vacuum (UHV), cluster-jet target chamber. CHICSi performs nuclear reaction experiments at storage rings. The telescopes consist of a first very thin, 10-14 mum Si detector, a second 300 mum (or possibly 500 pm) ion implanted Si detector supplemented by a 6 mm GSO(Ce) scintillator read out by a photodiode (PD) or by a third 300 mum Si detector. The telescopes provide full charge separation up to Z = 17 and mass resolution up to A = 9 in the energy range 0.7-60A MeV. The thin p-i-n diode detector, etched out from a 280 mum Si wafer, and the GSO/PD detector, both exclusively developed for CHICSi, provide an energy resolution less than or equal to 8%, while the standard 300 mum detectors have less than or equal to 2% energy resolution. Radiation stability of the Si detectors is confirmed up to an integrated flux of 10(10) alpha particles. The GSO detector has 70% light collection efficiency with the optical coupling to the PD a simple open, 0.2 mm, gap. A new method, developed to perform absolute energy calibration for the GSO/PD detector is presented. (C) 2003 Elsevier Science B.V. All rights reserved