Here we report on the results of the WEBT photo-polarimetric campaign targeting the blazar S5 0716+71, organized in March 2014 to monitor the source simultaneously in BVRI and near IR filters. The campaign resulted in an unprecedented dataset spanning ∼ 110 h of nearly continuous, multi-band observations, including two sets of densely sampled polarimetric data mainly in R filter. During the campaign, the source displayed pronounced variability with peak-to-peak variations of about 30% and "bluer-when-brighter" spectral evolution, consisting of a day-timescale modulation with superimposed hourlong microflares characterized by ∼ 0.1 mag flux changes. We performed an in-depth search for quasi-periodicities in the source light curve; hints for the presence of oscillations on timescales of ∼ 3 h and ∼ 5 h do not represent highly significant departures from a pure rednoise power spectrum. We observed that, at a certain configuration of the optical polarization angle relative to the positional angle of the innermost radio jet in the source, changes in the polarization degree led the total flux variability by about 2 h; meanwhile, when the relative configuration of the polarization and jet angles altered, no such lag could be noted. The microflaring events, when analyzed as separate pulse emission components, were found to be characterized by a very high polarization degree (> 30%) and polarization angles which differed substantially from the polarization angle of the underlying background component, or from the radio jet positional angle. We discuss the results in the general context of blazar emission and energy dissipation models.

The Water Cherenkov Detector Array (WCDA) is a major component of the Large High Altitude Air Shower Array Observatory (LHAASO), a new generation cosmic-ray experiment with unprecedented sensitivity, currently under construction. WCDA is aimed at the study of TeV -rays. In order to evaluate the prospects of searching for TeV -ray sources with WCDA, we present a projection of the one-year sensitivity of WCDA to TeV -ray sources from TeVCat using an all-sky approach. Out of 128 TeVCat sources observable by WCDA up to a zenith angle of , we estimate that 42 would be detectable in one year of observations at a median energy of 1 TeV. Most of them are Galactic sources, and the extragalactic sources are Active Galactic Nuclei (AGN).

Under the steady state condition, the spectrum of electrons is investigated by solving the continuity equation under the complex radiation of both the synchrotron and Compton processes. The resulted GRB spectrum is a broken power law in both the fast and slow cooling phases. On the basis of this electron spectrum, the spectral indices of the Band function in four different phases are presented. In the complex radiation frame, the detail investigation on physical parameters reveals that both the reverse shock photosphere model and the forward shock with strong coupling model can answer the α ∼ −1 problem. A possible marginal to fast cooling phase transition in GRB 080916C is discussed. The time resolved spectra in different pulses of GRB 100724B, GRB 100826A and GRB 130606B are investigated. We found that the flux is proportional to the peak energy in almost all pulses. The phases for different pulses are determined according to the spectral index revolution. We found the strong correlations between spectral indices and the peak energy in GRB 100826A, which can be explained by the Compton effect in the fast cooling phase. However, the complex scenario predicts a steeper index for the injected electrons, which challenges the acceleration mechanism in GRBs. ‡

A: A low power preamplifier solution for use with the rs-p4-0332-203r4 resistive charge distribution neutron detectors is presented in this work. The effects of the ground input impedance caused by the chip and the ground signal undershoot caused by the blocking capacitance are evaluated via simulations. For reference, a reasonable parameter configuration in the structure of a passive filter is sufficient to suppress the effects of both the input impedance and the undershoot. The power per channel in the preamplifier is limited to a maximum of 39 mW. Finally, measurement resolution of 6.8 mm is obtained for the detector.

A: We have developed multi-channel signal acquisition with a coincidence digital circuit for a two-dimensional detector array of the small-angle neutron scattering spectrometer (SANS) of the Institute of Nuclear Physical Chemistry at the Chinese Academy of Engineering Physics. This paper discusses how to determine such factors as the coincidence time window and program dead time according to the characteristics of the detector signal and how to correct the timer to realize the data coincidence. The whole system can support up to 192 analog channels connected to a fast analog-to-digital converter, supporting speeds of 50 MSPS for each channel managed by a fieldprogrammable gate array (FPGA). The internal clock of the FPGA is 50 MHz and the time accuracy is 20 ns. Preliminary experiments are carried out and the results are presented and discussed. The whole design can fully meet the needs of the spectrometer.