Zheng-Guo Hu

A first principles study of the influence of alloying elements on TiAl: site preference

The electronic structure and binding energy of a number of TiAl-X alloy systems (X=V, Cr, Mn, Fe, Co, Ni, Y, Zr, Nb, Mo, Hf, Ta, W, Ga, Ge, In or Sb) were calculated using the discrete variational cluster method, based on the local density approximation of the density functional theory. The site preference of the ternary additions to TiAl was investigated by means of the binding energy data and the Bragg-Williams model. The results showed that Y, Zr, Nb, Mo and Sb preferentially occupy the Ti sublattice sites, Ga and In occupy the Al sublattice sites, while V, Mn, Cr, Co and Ge may occupy either site, depending on the Ti/Al ratio. Investigation of the total and local densities of states for representative elements showed that the substitution behaviour of ternary additions in TiAl is determined by the electronic structure of the systems. The present predictions of the site preference of alloying elements in TiAl show good agreement with the most recent experimental findings

Nucleotide Sequence and Transcriptional Analysis of a Putative Basic DNA-Binding Protein of Helicoverpa armigera Nucleopolyhedrovirus

A putative basic DNA-binding protein (BDBP) gene was identified in the fragment EcoRI-K of the Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus (HearNPV) genome. The ORF is 330 nucleotides long encoding a basic protein of 109 amino acids with a molecular mass of 11.6 kDa. It is the first BDBP identified in single nucleocapsid NPVs and a homologue of Autographa californica MNPV (AcMNPV) P6.9. A consensus late transcription motif, ATAAG, was found at 57 nt upstream of the translational start codon and a polyadenylation signal was observed at 172 nt downstream of the stop codon. A major transcript of 620 nt was first observed in HearNPV-infected Hz2e5 cells 16 h post infection. Primer extension analysis revealed that this transcript initiated from the first residue of the consensus ATAAG late transcription start motif. Comparison with other baculoviral BDBPs showed that they all contained two conserved cAMP- and cGMP-dependent protein kinase phosphorylation motifs, R-R-R-S. The HearNPV P6.9 homologue is the longest BDBP found so far in baculoviruses.

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

In this paper, we present direct mass measurements of neutron-rich 86Kr projectile fragments conducted at the HIRFL-CSR facility in Lanzhou by employing the Isochronous Mass Spectrometry (IMS) method. The new mass excesses of 52–54Sc nuclides are determined to be −40492(82), −38928(114), −34654(540) keV, which show a significant increase of binding energy compared to the reported ones in the Atomic Mass Evaluation 2012 (AME12). In particular, 53Sc and 54Sc are more bound by 0.8 MeV and 1.0 MeV, 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.

Study of time resolution by digital methods with a DRS4 module

A new Digital Pulse Processing(DPP) module has been developed, based on a domino ring sampler version 4 chip(DRS4), with good time resolution for La Br3 detectors, and different digital timing analysis methods for processing the raw detector signals are reported. The module, composed of an eight channel DRS4 chip, was used as the readout electronics and acquisition system to process the output signals from XP20D0 photomultiplier tubes(PMTs). Two PMTs were coupled with La Br3 scintillators and placed on opposite sides of a radioactive positron22 Na source for 511 ke V γ-ray tests. By analyzing the raw data acquired by the module, the best coincidence timing resolution is about 194.7 ps(FWHM), obtained by the digital constant fraction discrimination(d CFD) method,which is better than other digital methods and analysis methods based on conventional analog systems which have been tested. The results indicate that it is a promising approach to better localize the positron annihilation in positron emission tomography(PET) with time of flight(TOF), as well as for scintillation timing measurement,such as in TOF-?E and TOF-E systems for particle identification, with picosecond accuracy timing measurement.Furthermore, this module is more simple and convenient than other systems.A new Digital Pulse Processing (DPP) module has been developed, based on a domino ring sampler version 4 chip (DRS4), with good time resolution for LaBr3 detectors, and different digital timing analysis methods for processing the raw detector signals are reported. The module, composed of an eight channel DRS4 chip, was used as the readout electronic and acquisition system to process the output signals from XP20D0 Photomultiplier Tubes (PMTs). Two PMTs were coupled with LaBr3 scintillator and placed face to face on both sides of a radioactive positron 22Na source for 511 keV gama ray tests. By analyzing the raw data acquired by the module, the best coincidence timing resolution is about 194.7 ps (FWHM), obtained by the digital constant fraction discrimination (dCFD) method, which is better than other digital methods and analysis methods based on conventional analog systems which have been tested. The results indicate that it is a promising approach to better localize the positron annihilation in positron emission tomography (PET) with time of flight (TOF), as well as for scintillation timing measurement, such as in TOF-DeltaE and TOF-E systems for particle identification, with picosecond accuracy timing measurement. Furthermore, this module is more simple and convenient than other systems.A new Digital Pulse Processing (DPP) module has been developed, based on a domino ring sampler version 4 chip (DRS4), with good time resolution for LaBr3 detectors, and different digital timing analysis methods for processing the raw detector signals are reported. The module, composed of an eight channel DRS4 chip, was used as the readout electronics and acquisition system to process the output signals from XP20D0 photomultiplier tubes (PMTs). Two PMTs were coupled with LaBr3 scintillators and placed on opposite sides of a radioactive positron 22Na source for 511 keV γ-ray tests. By analyzing the raw data acquired by the module, the best coincidence timing resolution is about 194.7 ps (FWHM), obtained by the digital constant fraction discrimination (dCFD) method, which is better than other digital methods and analysis methods based on conventional analog systems which have been tested. The results indicate that it is a promising approach to better localize the positron annihilation in positron emission tomography (PET) with time of flight (TOF), as well as for scintillation timing measurement, such as in TOF-ΔE and TOF-E systems for particle identification, with picosecond accuracy timing measurement. Furthermore, this module is more simple and convenient than other systems.

Study of time resolution by digital methods with DRS4 system

A new Digital Pulse Processing(DPP) module has been developed, based on a domino ring sampler version 4 chip(DRS4), with good time resolution for La Br3 detectors, and different digital timing analysis methods for processing the raw detector signals are reported. The module, composed of an eight channel DRS4 chip, was used as the readout electronics and acquisition system to process the output signals from XP20D0 photomultiplier tubes(PMTs). Two PMTs were coupled with La Br3 scintillators and placed on opposite sides of a radioactive positron22 Na source for 511 ke V γ-ray tests. By analyzing the raw data acquired by the module, the best coincidence timing resolution is about 194.7 ps(FWHM), obtained by the digital constant fraction discrimination(d CFD) method,which is better than other digital methods and analysis methods based on conventional analog systems which have been tested. The results indicate that it is a promising approach to better localize the positron annihilation in positron emission tomography(PET) with time of flight(TOF), as well as for scintillation timing measurement,such as in TOF-?E and TOF-E systems for particle identification, with picosecond accuracy timing measurement.Furthermore, this module is more simple and convenient than other systems.A new Digital Pulse Processing (DPP) module has been developed, based on a domino ring sampler version 4 chip (DRS4), with good time resolution for LaBr3 detectors, and different digital timing analysis methods for processing the raw detector signals are reported. The module, composed of an eight channel DRS4 chip, was used as the readout electronic and acquisition system to process the output signals from XP20D0 Photomultiplier Tubes (PMTs). Two PMTs were coupled with LaBr3 scintillator and placed face to face on both sides of a radioactive positron 22Na source for 511 keV gama ray tests. By analyzing the raw data acquired by the module, the best coincidence timing resolution is about 194.7 ps (FWHM), obtained by the digital constant fraction discrimination (dCFD) method, which is better than other digital methods and analysis methods based on conventional analog systems which have been tested. The results indicate that it is a promising approach to better localize the positron annihilation in positron emission tomography (PET) with time of flight (TOF), as well as for scintillation timing measurement, such as in TOF-DeltaE and TOF-E systems for particle identification, with picosecond accuracy timing measurement. Furthermore, this module is more simple and convenient than other systems.A new Digital Pulse Processing (DPP) module has been developed, based on a domino ring sampler version 4 chip (DRS4), with good time resolution for LaBr3 detectors, and different digital timing analysis methods for processing the raw detector signals are reported. The module, composed of an eight channel DRS4 chip, was used as the readout electronics and acquisition system to process the output signals from XP20D0 photomultiplier tubes (PMTs). Two PMTs were coupled with LaBr3 scintillators and placed on opposite sides of a radioactive positron 22Na source for 511 keV γ-ray tests. By analyzing the raw data acquired by the module, the best coincidence timing resolution is about 194.7 ps (FWHM), obtained by the digital constant fraction discrimination (dCFD) method, which is better than other digital methods and analysis methods based on conventional analog systems which have been tested. The results indicate that it is a promising approach to better localize the positron annihilation in positron emission tomography (PET) with time of flight (TOF), as well as for scintillation timing measurement, such as in TOF-ΔE and TOF-E systems for particle identification, with picosecond accuracy timing measurement. Furthermore, this module is more simple and convenient than other systems.

Analysis of digital timing methods with DRS4 module

A new Digital Pulse Processing(DPP) module has been developed, based on a domino ring sampler version 4 chip(DRS4), with good time resolution for La Br3 detectors, and different digital timing analysis methods for processing the raw detector signals are reported. The module, composed of an eight channel DRS4 chip, was used as the readout electronics and acquisition system to process the output signals from XP20D0 photomultiplier tubes(PMTs). Two PMTs were coupled with La Br3 scintillators and placed on opposite sides of a radioactive positron22 Na source for 511 ke V γ-ray tests. By analyzing the raw data acquired by the module, the best coincidence timing resolution is about 194.7 ps(FWHM), obtained by the digital constant fraction discrimination(d CFD) method,which is better than other digital methods and analysis methods based on conventional analog systems which have been tested. The results indicate that it is a promising approach to better localize the positron annihilation in positron emission tomography(PET) with time of flight(TOF), as well as for scintillation timing measurement,such as in TOF-?E and TOF-E systems for particle identification, with picosecond accuracy timing measurement.Furthermore, this module is more simple and convenient than other systems.A new Digital Pulse Processing (DPP) module has been developed, based on a domino ring sampler version 4 chip (DRS4), with good time resolution for LaBr3 detectors, and different digital timing analysis methods for processing the raw detector signals are reported. The module, composed of an eight channel DRS4 chip, was used as the readout electronic and acquisition system to process the output signals from XP20D0 Photomultiplier Tubes (PMTs). Two PMTs were coupled with LaBr3 scintillator and placed face to face on both sides of a radioactive positron 22Na source for 511 keV gama ray tests. By analyzing the raw data acquired by the module, the best coincidence timing resolution is about 194.7 ps (FWHM), obtained by the digital constant fraction discrimination (dCFD) method, which is better than other digital methods and analysis methods based on conventional analog systems which have been tested. The results indicate that it is a promising approach to better localize the positron annihilation in positron emission tomography (PET) with time of flight (TOF), as well as for scintillation timing measurement, such as in TOF-DeltaE and TOF-E systems for particle identification, with picosecond accuracy timing measurement. Furthermore, this module is more simple and convenient than other systems.A new Digital Pulse Processing (DPP) module has been developed, based on a domino ring sampler version 4 chip (DRS4), with good time resolution for LaBr3 detectors, and different digital timing analysis methods for processing the raw detector signals are reported. The module, composed of an eight channel DRS4 chip, was used as the readout electronics and acquisition system to process the output signals from XP20D0 photomultiplier tubes (PMTs). Two PMTs were coupled with LaBr3 scintillators and placed on opposite sides of a radioactive positron 22Na source for 511 keV γ-ray tests. By analyzing the raw data acquired by the module, the best coincidence timing resolution is about 194.7 ps (FWHM), obtained by the digital constant fraction discrimination (dCFD) method, which is better than other digital methods and analysis methods based on conventional analog systems which have been tested. The results indicate that it is a promising approach to better localize the positron annihilation in positron emission tomography (PET) with time of flight (TOF), as well as for scintillation timing measurement, such as in TOF-ΔE and TOF-E systems for particle identification, with picosecond accuracy timing measurement. Furthermore, this module is more simple and convenient than other systems.

Investigation of LaBr3:Ce scintillator with excellent property

In order to satisfy high precision requirement for the modern nuclear physics experiment detectors and radiologic imaging technology equipments, we do some researches in improving the resolution of the detector with LaBr3:Ce scintillator.

Experimental Study of Two-alpha Emission from High-lying Excited States of 17,18 Ne

The experiments of two-alpha emission from Ne-17,Ne-18 excited levels were performed at the HIRFL-RIBLL facility of the Institute of Modern Physics, Lanzhou. The beams of Ne-17 at the energy of 49.9 MeV/u and Ne-18 at 51.8 MeV/u bombarded a Au-197 target to populate excited states of Ne-17,Ne-18 via Coulomb excitation. Complete kinematics measurements were achieved by the detectors of a silicon strip and CsI+PIN array. The experimental results combined with simple MC simulations show the characteristic of sequential two-alpha emission via O-14 excited states for Ne-18. The results of two-alpha emission from Ne-17 are preliminary and need further analyses.