[en] A contrastive research on two-proton (2p) emissions from excited states of the even-Z nucleus ²⁸S and its one-proton daughter, the odd-Z nucleus ²⁷P was performed by complete-kinematics measurements. The opening angles as well as relative momenta between two emitted protons and invariant masses of decaying systems were reconstructed through the event-by-event analysis of heavy fragments coincident with two protons. With the help of Monte Carlo simulations, results show a diproton-type decay with the branching ratio of 20₋₇⁺⁶% for ²⁸S while mainly three-body simultaneous decay in the phase space and/or 2p sequential emission for ²⁷P. Present results show that the diproton correlations may result from the proton configuration in the initial state like 2p skin/halo structure rather than the deformed orbit

[en] Masses of A=2Z-1 proton-rich nuclides were measured with the experimental cooler storage ring CSRe in Lanzhou by employing the isochronous mass spectrometry (IMS) method. The short-lived proton-rich nuclides were produced via ⁷⁸Kr projectile fragmentation, separated in the radioactive beam line RIBLL2 and then stored in CSRe. A typical mass resolving power of R=m/Δm∼1.7.10⁵ was achieved. After the improvement of the stability of CSRe dipole magnet power supplies, a new measurement with ⁵⁸Ni projectile fragments was carried out. The data analysis methods for both experiments are presented.

[en] A method is presented for the measurement of differential cross-sections of heavy ion elastic scattering induced by Radioactive Ion Beams (RIBs) on the Radioactive Ion Beam Line in Lanzhou (RIBLL) at the Heavy-Ion Research Facility in Lanzhou (HIRFL). The disadvantages of broad beam profiles and limited intensities of the RIBs were overcome using large area detectors, two Parallel-Plate Avalanche Counters (PPACs), two double-sided silicon strip detector (DSSD) telescopes, incorporated with Monte Carlo simulations. The PPACs were used to determine the direction and position of the beam particles. The DSSD telescopes were used to measure scattered particles. Small corrections for the misalignment of detectors and the data normalization were made by assuming the pure Rutherford scattering at very forward angles. The method is suitable for the measurement of the cross-sections on heavy targets at low and intermediate energies, and it has been successfully applied to measure the angular distribution of elastic scattering of ⁷Be on Pb target at E_lab=17.9MeV/u.

[en] Highlights: • A ΔE-E telescope consists of a 40 × 40 DSSD and a 8 × 8 CsI (Tl) • The performance of DSSD and CsI (Tl) array are given out. • A test experiment is performed in RIBLL. The secondary beam ⁹C, ⁸B, ⁷Be, ⁶li are clearly identified. -- Abstract: A telescope array composed of a silicon strip detector and scintillator crystals is dedicated to detect reaction products induced by radioactive ion beams. The silicon strip detector has a thickness of 1000 μm and is divided into 40 × 40 strips with 1 mm resolution. The crystal array consists of 8 × 8 CsI (Tl) crystals with readouts by photo-multiplier tubes. The design and performance of this telescope array are described

[en] The stellar ¹⁴O (α, p) ¹⁷F reaction is thought to be one of the most important breakout reactions from the Hot CNO cycles into the rp-process in Type I X-ray bursters. In the present work, the properties of proton resonances in ¹⁸Ne have been investigated efficiently by utilizing a technique of proton resonant elastic scattering with a ¹⁷F radioactive-ion (RI) beam and a thick proton target. A 4.22 MeV/nucleon ¹⁷F RI beam, which was produced via a projectile-fragmentation reaction and experiencing a series of energy degradation, was separated by a Radioactive Ion Beam Line in Lanzhou (RIBLL) and bombarded a (CH₂)_n target. Energy spectra of the recoiled protons were measured by two sets of ΔE-E silicon telescope at center-of-mass scattering angles of θ _c.m. ∼ 175 ± 5 , θ _c.m. ∼ 152 ± 8 , respectively. Several proton resonances in ¹⁸Ne were observed, and their resonant parameters have been determined by an R-matrix analysis of the differential cross-sections. A doublet structure around 7.10 MeV has been identified and thought to be one state at 7.05 MeV (2⁺) and another one at 7.12 MeV (4⁺). The presently calculated total reaction rates of ¹⁴O (α, p) ¹⁷F are, at least, a factor of 1.2 ∝ 1.9 larger than the previous ones in a temperature region of 1.7 ∝ 3.0 GK mainly owing to the contribution from the 7.05 MeV (2⁺) state. This result implies that this breakout reaction may play a more important role than previously expected. (orig.)

[en] The precise calibration of angular distribution of heavy-ion elastic scattering induced by Radioactive Ion Beams (RIBs) at energies around Coulomb barrier on the Radioactive Ion Beam Line in Lanzhou (RIBLL) at the Heavy-Ion Research Facility in Lanzhou (HIRFL) is presented. The beam profile and the scattering angles on the target are deduced by a measurement with two Multi Wire Proportional Chambers (MWPC), and four sets of detector telescopes (including Double-sided Silicon Strip Detectors (DSSD) placed systematically along the beam line, incorporating with Monte Carlo simulation. The MWPCs were used to determine the beam trajectory before the target, and the energies and the positions of scattered particles on the detectors were measured by the DSSDs. Minor corrections on the beam spot and the detector position are performed by assuming the pure Rutherford scattering at angles which are smaller than the related grazing angle. This method is applied for the elastic scattering of "1"7F on "8"9Y target at E_l_a_b=59 MeV and 50 MeV.

[en] The β-delayed two-proton emission from ²²Al was investigated experimentally through the implantation-decay method. A β-delayed two-proton decay branch from ²²Al were identified based on the coincidence of the charged particles and γ-ray signals. The relative momentum ($q_{pp}$) and the opening angle (${\theta }_{pp}$) distributions of the two β-delayed protons are measured and a strong peak at $q_{pp}\sim 20\text{MeV/c}$, as well as a peak at ${\theta }_{pp}\sim {30}^{\circ }$ are observed clearly. The β-delayed ²He emission from ²²Al with a probability of 29 (13)% by fitting the experimental data with the results of Monte Carlo simulations.

[en] A gas-target system has been newly developed and installed at a Radioactive Ion Beam Line in Lanzhou (RIBLL), which makes RIBLL capable of delivering intense, low-energy RIBs for nuclear astrophysics studies. A 1.7×10⁴-pps intensity ²²Na RI beam has been achieved in a commissioning run. With further improvements, a 10⁵-pps intensity of some RI beams with mass A<30 (close to the line of β-stability) can be expected in the near future. Some detection equipment including Germanium and Silicon arrays (or balls) available (or to be constructed) at IMP are briefly introduced. A new low-energy radioactive beam line in China is now ready for nuclear astrophysics studies.

[en] Direct mass measurements of ⁷⁸Kr projectile fragments have been performed in the recently commissioned storage ring CSRe employing the isochronous mass spectrometry method. A new data-analysis technique has been developed to correct the drifts in the revolution frequencies caused by instabilities of the magnetic fields in the CSRe, thus yielding a mass resolving power of R=m/Δm∼1.7x10⁵ (sigma). Masses for ⁴⁵V, ⁴⁷Cr, ⁴⁹Mn and ⁵¹Fe nuclei are determined with a relative mass precision of δm/m∼2x10^-7 (sigma) which is an improvement by a factor of ∼2 compared to the literature values.