A pilot experiment of mass measurement was performed at CSRe with the method of isochronous mass spectrometry. The secondary fragments produced via RIBLL2 with the primary beam of 400 MeV/u 36Ar delivered by CSRm were injected into CSRe. The revolution periods of the stored ions,which depend on the mass-to-charge ratios of the stored ions,were measured with a time-of-flight detector system. The results show that the mass resolution around 8×10-6 for △m/m is achieved.
In an effective Lagrangian model we find that the N*(1535) resonance contribution might be important to the interpretation of the present data of the pp → ppη′ and pn → dφ reactions. The strong coupling strength of N*(1535) to η′ and φ are indicated, and the possible implication to the intrinsic component of N*(1535) is explored. These results may provide hints to the real origin of the OZI rule violation. It is stressed that further measurements could be performed at the Cooling Storage Ring (CSR) at Lanzhou of China.
To achieve a better time resolution of a scintillator-bar detector for a neutron wall at the external target facility of HIRFL-CSR,we have carried out a detailed study of the photomultiplier,the wrapping material and the coupling media. The timing properties of a scintillator-bar detector have been studied in detail with cosmic rays using a high and low level signal coincidence. A time resolution of 80 ps has been achieved in the center of the scintillator-bar detector.
The Isochronous Mass Spectrometry is a high accurate mass spectrometer. A secondary electrons time detector has been developed and used for mass measurements. Secondary electrons from a thin carbon foil are accelerated by an electric field and deffected 180° by a magnetic field onto a micro-channel plate. The time detector has been tested with alpha particles and a time resolution of 197 ps (FWHM) was obtained in the laboratory. A mass resolution around 8×10-6 for m/m was achieved by using this time detector in a pilot mass measurement experiment.
With the commissioning of the Cooler Storage Ring at the Heavy Ion Research Facility in Lanzhou (HIRFL-CSR),a pilot experiment operating the CSRe in isochronous mode to test the power of HIRFL-CSR for measuring the mass of the short-lived nucleus was performed in December of 2007. The fragments with A/q = 2 of 36Ar were injected into CSRe and their revolution frequencies were measured with a fast time pick-up detector with a thin foil in the circulating path of the ions. The preliminary result is presented. The result shows the potential of CSRe for mass measurements of short-lived nuclei.
TU Xiao-lin1,2, XU Hu-shan1, , WANG Meng1, XIA Jia-wen1, MAO Rui-shi1, YUAN You-jin1, HU Zheng-guo1, LIU Yong1, ZHANG Hong-bin1, ZANG Yong-dong1,2, ZHAO Tie-cheng1, ZHANG Xue-ying1, FU Fen1, YANG Jian-cheng1, MAO Li-jun1, XIAO Chen1,2, XIAO Guo-qing1, ZHAO Hong-wei1, ZHAN Wen-long1(1 Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
The luminosity for a WASA-at-COSY experiment involving the pd reaction at 2.14 GeV proton-beam energy is determined by the forward pd elastic scattering, which yields an average beam-on-target value of [5.2±0.3(stat)±0.3(syst)]×1030 s-1 cm-2. In addition, the forward pd elastic-scattering angular distribution is obtained with four-momentum transfer squared -t between 0.16 (GeV/c)2 and 0.78 (GeV/c)2 at this beam energy, which is compared with other experimental data and the pd double scattering model.
