24721947
Development of the Central Task Processing Unit for space-borne Gamma-Ray Burst polarimeter, POLAR
POLAR, a joint European-Chinese experiment, is a novel compact space-borne Compton polarimeter conceived and optimized for detection of the prompt emission of Gamma-Ray Bursts (GRB) and precise measurements of polarization in the hard X-ray energy range 50-500 keV. The complete instrument consists of two parts: internal one, placed inside spacelab and the detector itself, placed outside spacelab, called respectively IBOX and OBOX. The OBOX constitutes of 25 frontend electronic modules (FEE), high voltage and low voltage power supplies and the Central Task Processing Unit. The main functions of Central Task Processing Unit system are defined as follows: communication and transfer of data to IBOX, communication with all frontends, analysis of trigger signals and generation of global trigger signals, data acquisition, synchronizing of all frontends and control of power supplies. The functional requirements are fulfilled by three individual FPGA chips named respectively to their functions: Concentrator, Trigger and CPU. This article presents description of the Central Task Processing Unit hardware design and brief introduction to main components of the firmware developed for this device. Ongoing integration activities of the device with the complete POLAR instrument proved that all basic functions are working correctly. The qualification model of the instrument has been constructed and currently undergoes verification and validation tests in view of planned flight onboard the Chinese spacelab TG-2 scheduled for 2015.
119237527
SVOM gamma ray monitor
The space-based multi-band astronomical Variable Object Monitor (SVOM) mission is dedicated to the detection, localization and broad-band study of gamma-ray bursts (GRBs) and other high-energy transient phenomena. The gamma ray monitor (GRM) onboard is designed to observe GRBs up to 5 MeV. With this instrument, one of the key GRB parameters, Epeak, can be easily measured in the hard X-ray band. It can achieve a detection rate of 100 GRBs per year which ensures the scientific output of SVOM.
118558798
A possible NN*(1440) quasi-molecular state
Inspired by the recent observation of a narrow resonance-like structure around 2360 MeV in the pn → dπ0π0 cross section, the possibility of forming a NN*(1440) quasi-molecular state is investigated by using a meson exchange model in which the π, σ, ρ and ω exchanges in t- and u-channels are considered. By adopting the coupling constants extracted from the relevant NN scattering and N*(1440) decay data, it is found that a deuteron-like quasi-molecular state of NN*(1440) with a binding energy in the range of 2 ∼ 67 MeV can be formed. Therefore, it is speculated that the observed structure around 2360 MeV might be or may have a large component of the NN*(1440) quasi-molecular state.
117856805
A cosmic ray test platform based on high time resolution MRPC technology
In order to test the performance of detector prototypes in a laboratory environment, we design and build a large area (90 cm×52 cm) test platform for cosmic rays based on a well-designed Multi-gap Resistive Plate Chamber (MRPC) with excellent time resolution and a high detection efficiency for minimum ionizing particles. The time resolution of the MRPC module used is tested to be ~80 ps, and the position resolution along the strip is ~5 mm, while the position resolution perpendicular to the strip is ~12.7 mm. The platform constructed by four MRPC modules can be used for tracking cosmic rays with a spatial resolution of ~6.3 mm, and provide a reference time ~40 ps.
11648919
Complementarity of LHC and EDMs for exploring Higgs CP violation
A bstractWe analyze the constraints on a CP-violating, flavor conserving, two Higgs doublet model from the measurements of Higgs properties and from the search for heavy Higgs bosons at LHC, and show that the stronger limits typically come from the heavy Higgs search channels. The limits on CP violation arising from the Higgs sector measurements are complementary to those from EDM measurements. Combining all current constraints from low energy to colliders, we set generic upper bounds on the CP violating angle which parametrizes the CP odd component in the 126 GeV Higgs boson.
36920558
Determination of the Newtonian gravitational constant G with time-of-swing method.
We present a new value of the Newtonian gravitational constant G by using the time-of-swing method. Several improvements greatly reduce the uncertainties: (1) measuring the anelasticity of the fiber directly; (2) using spherical source masses minimizes the effects of density inhomogeneity and eccentricities; (3) using a quartz block pendulum simplifies its vibration modes and minimizes the uncertainty of inertial moment; (4) setting the pendulum and source masses both in a vacuum chamber reduces the error of measuring the relative positions. By two individual experiments, we obtain G = 6.673 49(18) x 10;{-11} m;{3} kg;{-1} s;{-2} with a standard uncertainty of about 2.6 parts in 10;{5}.
119114407
Exploring the Higgs sector of a most natural NMSSM and its prediction on Higgs pair production at the LHC
A bstractAs a most natural realization of the Next-to Minimal Supersymmetry Standard Model (NMSSM), λ-SUSY is parameterized by a large λ around one and a low tan β below 10. In this work, we first scan the parameter space of λ-SUSY by considering various experimental constraints, including the limitation from the Higgs data updated by the ATLAS and CMS collaborations in the summer of 2014, then we study the properties of the Higgs bosons. We get two characteristic features of λ-SUSY in experimentally allowed parameter space. One is the triple self coupling of the SM-like Higgs boson may get enhanced by a factor over 10 in comparison with its SM prediction. The other is the pair production of the SM-like Higgs boson at the LHC may be two orders larger than its SM prediction. All these features seems to be unachievable in the Minimal Supersymmetric Standard Model and in the NMSSM with a low λ. Moreover, we also find that naturalness plays an important role in selecting the parameter space of λ-SUSY, and that the Higgs χ2 obtained with the latest data is usually significantly smaller than before due to the more consistency of the two collaboration measurements.