Quadrupole and magnetic moment measurements on spin-aligned projectile fragments

The Level Mixing Resonance (LMR) technique allows to determine ground-state nuclear moments by measuring the spin-polarization of the betaddecay, and starting from an initially aligned ensemble of nuclei. Using this new technique, the ratio of the quadrupole frequency to the magnetic moment of the neutron rich¹⁸N ground state has been measured: $\nu _Q /\mu (^{18} N\underline {Mg} ) = 1328(33)$ kHz/n.m. In order to measure the nuclear moments independently, the Nuclear Magnetic Resonance (NMR) and LMR techniques will be combined.     

Direct mass measurements of neutron-deficient 152Sm projectile fragments at the FRS-ESR facility

The FRS-ESR facility at GSI provides one of the most efficient methods for direct mass measurements. In the present experiment, exotic nuclei were produced via fragmentation of ¹⁵²Sm projectiles in a thick beryllium target at 500-600 MeV/u, separated in-flight with the fragment separator FRS, and injected into the storage-cooler ring ESR. Time-resolved Schottky Mass Spectrometry was applied for mass measurements of stored and electron-cooled bare and few-electron ions. 373 different nuclides were identified by means of the spectra of their revolution frequencies. Masses for 18 nuclides (⁸⁴Zr, ⁹²Ru, ⁹⁴Rh, ^107,108,110Sb, ^111,112,114I, ¹¹⁸Ba, ^122,123La, ¹²⁴Ce, ¹²⁷Pr, ¹²⁹Nd, ¹³²Pm, ¹³⁴Sm, ¹³⁷Eu) have been determined for the first time. Masses for ^111,112I and ¹¹³Xe have been obtained via known α-decay energies. The experiment and first results will be presented.     

Extraction of thermalized projectile fragments from gas

The NSCL gas cell and quadrupole ion-guide system has been used to study the thermalization of fast nuclear reaction products in a buffer gas. The fraction of radioactive ions that can be extracted from the gas cell is dramatically suppressed by space charge created by the stopping ions. The results of a review of the ion yields from the NSCL and from other gas cells from the literature with different sizes and different incident particle energies shows an overall consistency with a dramatic decline in extraction efficiency at high ionization rates.     

Single source emission of proton projectile fragments in nucleus-emulsion interactions

The projected angular distribution and transverse momentum distribution of proton projectile fragments produced in 3.7A GeV 16O,500A MeV 56Fe,and 1.7A GeV 84Kr induced by different kinds of emulsion target(H,CNO,and AgBr) interactions are investigated.It is found that the projected angular distribution and transverse momentum distribution can be well represented by a single Gaussian distribution.Comparison of transverse momentum distribution with the Maxwell-Boltzmann distribution reveals that proton projectile fragments are emitted from a single-temperature emission source.The temperature is different for different colliding systems,and linearly depends on the target size.     

Yields of projectile fragments in sulphur-emulsion interactions at 3.7 A GeV

This work presents the basic characteristics of singly,doubly and heavily charged projectile fragments(PFs) emitted in inelastic interactions of ~(32)S ions with photo-emulsion nuclei at Dubna energy(3.7 A GeV).Our experimental data are compared with the corresponding data for other projectiles at the same incident energy.The study of mean multiplicities of different charged PFs against the projectile mass shows a power-law relationship.The multiplicity distributions of singly and doubly charged PFs have been fitted well with a Gaussian distribution function.The yields of PFs broken up from the interactions of ~(32)S projectile nuclei with different target nuclei are studied.The beam energy dependence in terms of the various order moments is studied as well.     

On-line isotope separation of projectile fragments produced in relativistic heavy-ion reactions

A new on-line isotope separator was constructed and used successfully for the study on short-lived isotopes at the Bevalac at Lawrence Berkeley Laboratory. The isotopes were produced through projectile fragmentation processes of high energy heavy-ion reactions. Various isotopes were rigidity-separated by use of a beam line and, finally, the desired single isotope was range analyzed to stop in a catcher. A large number of β-emitting²¹F nuclei were successfully collected and the nuclear lifetime was determined by detecting β-rays.     

Polarization in projectile fragmentation andg-factor measurements for neutron-rich nuclei

A method to produce beams of polarized unstable nuclei was developed, which fully exploits the advantageous features of the projectile fragmentation reaction. The method was applied tog-factor measurements of several neutron-rich nuclei. We present experimental results so far obtained and discuss capabilities and limitations the present polarization method has.     

Search for projectile fragments with fractional charge in relativistic heavy ion collisions

We measured the charge of about 35 000 projectile fragments with Z5e produced by 14.5 GeV/nucleon and 200 GeV/nucleon ¹⁶O beams in a Pb target using CR39 plastic nuclear track detectors. A minimum track length of 3 mm in the detector without nuclear interaction was required. No evidence for fragments carrying a fractional charge was found.     

Characteristics of alpha projectile fragments emission in interaction of nuclei with emulsion

The properties of the relativistic alpha fragments produced in interactions of ⁸⁴Kr at around 1 A GeV in nuclear emulsion are investigated. The experimental results are compared with the similar results obtained from various projectiles with emulsion interactions at different energies. The total, partial nuclear cross-sections and production rates of alpha fragmentation channels in relativistic nucleus-nucleus collisions and their dependence on the mass number and initial energy of the incident projectile nucleus are investigated. The yields of multiple alpha fragments emitted from the interactions of projectile nuclei with the nuclei of light, medium and heavy target groups of emulsion-detector are discussed and they indicate that the projectile-breakup mechanism seems to be free from the target mass number. It is found that the multiplicity distributions of alpha fragments are well described by the Koba-Nielsen-Olesen (KNO) scaling presentation. The mean multiplicities of the freshly produced or newly created charged secondary particles, normally known as shower and secondary particles associated with target in the events where the emission of alpha fragments were accompanied by heavy projectile fragments having Z ≥ 3 seem to be constant as the alpha fragments multiplicity increases, and exhibit a behavior independent of the alpha fragments multiplicity.     

Forward hadron calorimeter for measurements of projectile spectators in heavy-ion experiment

The construction and performance of a modular hadron calorimeter for NA61 experiment at CERN are described. The calorimeter consists of individual lead/scintillator sandwich modules with the sampling satisfying the compensating condition. The light from the individual scintillator tiles is captured and transported with the WLS-fibers embedded in the scintillator grooves. The light readout is done by avalanche micro-pixel photodiodes. The construction ensures a fine transverse granulation of the calorimeter and a longitudinal segmentation of each module in 10 independent sections. The results of beam tests of the calorimeter prototype are presented.     

Inclusive and exclusive measurements in the projectile breakup of 7Li

The inclusive and exclusive measurements were carried out for ⁷Li projectile breakup on ²⁷Al target at 48 MeV. In the inclusive data we have observed a broad peak around the beam velocity for alphas and tritons. The exclusive data for alpha-triton coincidences show good agreement with the post-form DWBA theory of breakup reactions.     

Direct mass measurements of neutron-rich ~(86)Kr projectile fragments and the persistence of neutron magic number N=32 in Sc isotopes

In this paper, we present direct mass measurements of neutron-rich86 Kr projectile fragments conducted at the HIRFL-CSR facility in Lanzhou by employing the Isochronous Mass Spectrometry(IMS) method. The new mass excesses of52-54 Sc nuclides are determined to be-40492(82),-38928(114),-34654(540) ke V, which show a significant increase of binding energy compared to the reported ones in the Atomic Mass Evaluation 2012(AME12).In particular,53 Sc and54Sc are more bound by 0.8 Me V and 1.0 Me V, respectively. The behavior of the two neutron separation energy with neutron numbers indicates a strong sub-shell closure at neutron number N =32 in Sc isotopes.     

Precision Penning trap mass measurements of rare isotopes produced by projectile fragmentation

The low-energy beam and ion trap facility LEBIT at NSCL/MSU is at present the only facility where precision experiments are performed with stopped rare isotope beams produced by fast-beam fragmentation. LEBIT combines high-pressure-gas stopping with advanced ion manipulation techniques to provide brilliant low-energy beams. So far these beams have mainly been used for mass measurements on short-lived rare isotopes with a 9.4T Penning trap mass spectrometer. Recent examples include ^70m Br , located at the proton dripline, ³²Si and the iron isotopes ^63-65Fe . While the measurement of ³²Si helps to solve a long-standing dispute over the validity of the isobaric multiplet mass equation (IMME) for the A = 32 , T = 2 multiplet, the mass measurements of ^65m,g Fe marked the first time a nuclear isomeric state has been discovered by Penning trap mass spectrometry.     

The eight first vibrational states of the water molecule: measurements and analysis

In this work the spectrum of the water molecule has been the subject of extensive experimental and theoretical investigations. More than 1500 transitions have been assigned in a far infrared emission spectrum recorded in the 50-500 cm⁻¹ region and experimental rotational energies have been obtained for the second triad of interacting states, (0 3 0), (1 1 0), and (0 1 1), up to J=10 using flame spectroscopy. These new data along with a large data set of already published experimental rotational energies, high-resolution infrared transitions, and microwave lines, involving the eight first vibrational states, have been analyzed using the theoretical formalism developed for water in a previous paper (J. Mol. Spectrosc. 206 (2001) 83), which accounts for the anomalous centrifugal distortion as well as for the Fermi- and Coriolis-type couplings.     

First precision mass measurements of refractory fission fragments

Atomic masses of 95-100Sr, 98-105Zr, and [corrected] 102-110Mo and have been measured with a precision of 10 keV employing a Penning trap setup at the IGISOL facility. Masses of 104,105Zr and 109,110Mo are measured for the first time. Our improved results indicate significant deviations from the previously published values deduced from beta end point measurements. The most neutron-rich studied isotopes are found to be significantly less bound (1 MeV) compared to the 2003 atomic mass evaluation. A strong correlation between nuclear deformation and the binding energy is observed in the two-neutron separation energy in all studied isotope chains.     

Angular distributions of light projectile fragments in deep inelastic Pb + Em interactions at 160 A GeV

The nuclear emulsion was exposed at CERN by the lead projectile at 160 A GeV. The angles between any pair of fragments with Z = 2-4 have been measured in the emulsion plane for the events which did not contain heavy fragments. The constant characterizing the normal angle (J) distribution of the fragment momentum projection onto the emulsion plane with respect to initial projectile momentum p₀ is found to be C_J = (0.37 - 0.02) mrad. Corresponding value C₀ = (121 - 6) MeV/c of nucleon momentum distribution in the lead nucleus coincides with that expected from Fermi momentum distribution for this nucleus. The peak in the pair-angle distribution of double-charged fragments, ⁸Be M 2!, is presented for the region of small angles (<0.1 mrad). The fraction of !-particles coming from the decay of the ground state ⁸Be is found to be (13 - 2)% of their whole number.     

Penning trap mass measurements of rare isotopes produced by projectile fragmentation with LEBIT at NSCL

The Low-Energy Beam and Ion Trap facility LEBIT at the NSCL at MSU has demonstrated that rare isotopes produced by fast-beam fragmentation can be slowed down and prepared for precision experiments with low-energy beams. High-pressure gas-stopping was combined with advanced ion manipulation techniques to carry out these studies with a high-precision 9.4-Tesla Penning trap mass spectrometer. The spectrometer has been used for a series of high precision mass measurements of short-lived neutron- and proton-rich isotopes during the past year. This paper presents an overview of the LEBIT facility and summarizes the first mass measurement results. The mass measurements of ⁸¹Se, where ground and isomeric states have been resolved, and of ⁸⁰As will be discussed in detail.     

非理想抛体的最佳抛射角

借助数值计算,给出有阻力、起点与终点在不同高度的抛体的最佳抛射角.     

The application of high-speed TV-holography to time-resolved vibration measurements

We describe an electronic speckle pattern interferometer (ESPI) system that has enabled non-harmonic vibrations to be measured with μs temporal resolution. The short exposure period and high framing rate of a high-speed camera at up to 40,500 frames per second allow low-power CW laser illumination and fibre-optic beam delivery to be used, rather than the high peak power pulsed lasers normally used in ESPI for transient measurement. The technique has been demonstrated in the laboratory and tested in preliminary industrial trials. The ability to measure vibration with high spatial and temporal resolution, which is not provided by techniques such as scanning laser vibrometry, has many applications in manufacturing design, and in an illustrative application described here revealed previously unmeasured “rocking” vibrations of a car door. It has been possible to make the measurement on the door as part of a complete vehicle standing on its own tyres, wheels and suspension, and where the excitation was generated by the running of the vehicle's own engine.