163 research outputs found
Isospin Effect on the Process of Multifragmentation and Dissipation at Intermediate Energy Heavy Ion Collisions
In the simulation of intermediate energy heavy ion collisions by using the
isospin dependent quantum molecular dynamics, the isospin effect on the process
of multifragmentation and dissipation has been studied. It is found that the
multiplicity of intermediate mass fragments for the neutron-poor
colliding system is always larger than that for the neutron-rich system, while
the quadrupole of single particle momentum distribution for the
neutron-poor colliding system is smaller than that of the neutron-rich system
for all projectile-target combinations studied at the beam energies from about
50MeV/nucleon to 150MeV/nucleon. Since depends strongly on isospin
dependence of in-medium nucleon-nucleon cross section and weakly on symmetry
potential at the above beam energies, it may serve as a good probe to extract
the information on the in-medium nucleon-nucleon cross section. The correlation
between the multiplicity of intermediate mass fragments and the total
numer of charged particles has the behavior similar to , which
can be used as a complementary probe to the in-medium nucleon-nucleon cross
section.Comment: 18 pages, 9 figure
Laser Direct Writing of Visible Spin Defects in Hexagonal Boron Nitride for Applications in Spin-Based Technologies
Optically addressable spins in two-dimensional hexagonal boron nitride (hBN)
attract widespread attention for their potential advantage in on-chip quantum
devices, such as quantum sensors and quantum network. A variety of spin defects
have been found in hBN, but no convenient and deterministic generation methods
have been reported for other defects except negatively charged boron vacancy
(). Here we report that by using femtosecond laser direct writing
technology, we can deterministically create spin defect ensembles with spectra
range from 550 nm to 800 nm on nanoscale hBN flakes. Positive single-peak
optically detected magnetic resonance (ODMR) signals are detected in the
presence of magnetic field perpendicular to the substrate, and the contrast can
reach 0.8%. With the appropriate thickness of hBN flakes, substrate and
femtosecond laser pulse energy, we can deterministically and efficiently
generate bright spin defect array. Our results provide a convenient
deterministic method to create spin defects in hBN, which will motivate more
endeavors for future researches and applications of spin-based technologies
such as quantum magnetometer array
A universal programmable Gaussian Boson Sampler for drug discovery
Gaussian Boson Sampling (GBS) exhibits a unique ability to solve graph
problems, such as finding cliques in complex graphs. It is noteworthy that many
drug discovery tasks can be viewed as the clique-finding process, making them
potentially suitable for quantum computation. However, to perform these tasks
in their quantum-enhanced form, a large-scale quantum hardware with universal
programmability is essential, which is yet to be achieved even with the most
advanced GBS devices. Here, we construct a time-bin encoded GBS photonic
quantum processor that is universal, programmable, and software-scalable. Our
processor features freely adjustable squeezing parameters and can implement
arbitrary unitary operations with a programmable interferometer. Using our
processor, we have demonstrated the clique-finding task in a 32-node graph,
where we found the maximum weighted clique with approximately twice the
probability of success compared to classical sampling. Furthermore, a
multifunctional quantum pharmaceutical platform is developed. This GBS
processor is successfully used to execute two different drug discovery methods,
namely molecular docking and RNA folding prediction. Our work achieves the
state-of-the-art in GBS circuitry with its distinctive universal and
programmable architecture which advances GBS towards real-world applications.Comment: 10 pages, 5 figure
Ground calibration of Gamma-Ray Detectors of GECAM-C
As a new member of GECAM mission, GECAM-C (also named High Energy Burst
Searcher, HEBS) was launched onboard the SATech-01 satellite on July 27th,
2022, which is capable to monitor gamma-ray transients from 6 keV to 6
MeV. As the main detector, there are 12 gamma-ray detectors (GRDs) equipped for
GECAM-C. In order to verify the GECAM-C GRD detector performance and to
validate the Monte Carlo simulations of detector response, comprehensive
on-ground calibration experiments have been performed using X-ray beam and
radioactive sources, including Energy-Channel relation, energy resolution,
detection efficiency, SiPM voltage-gain relation and the non-uniformity of
positional response. In this paper, the detailed calibration campaigns and data
analysis results for GECAM-C GRDs are presented, demonstrating the excellent
performance of GECAM-C GRD detectors.Comment: third versio
Neutrino Physics with JUNO
The Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton multi-purposeunderground liquid scintillator detector, was proposed with the determinationof the neutrino mass hierarchy as a primary physics goal. It is also capable ofobserving neutrinos from terrestrial and extra-terrestrial sources, includingsupernova burst neutrinos, diffuse supernova neutrino background, geoneutrinos,atmospheric neutrinos, solar neutrinos, as well as exotic searches such asnucleon decays, dark matter, sterile neutrinos, etc. We present the physicsmotivations and the anticipated performance of the JUNO detector for variousproposed measurements. By detecting reactor antineutrinos from two power plantsat 53-km distance, JUNO will determine the neutrino mass hierarchy at a 3-4sigma significance with six years of running. The measurement of antineutrinospectrum will also lead to the precise determination of three out of the sixoscillation parameters to an accuracy of better than 1\%. Neutrino burst from atypical core-collapse supernova at 10 kpc would lead to ~5000inverse-beta-decay events and ~2000 all-flavor neutrino-proton elasticscattering events in JUNO. Detection of DSNB would provide valuable informationon the cosmic star-formation rate and the average core-collapsed neutrinoenergy spectrum. Geo-neutrinos can be detected in JUNO with a rate of ~400events per year, significantly improving the statistics of existing geoneutrinosamples. The JUNO detector is sensitive to several exotic searches, e.g. protondecay via the decay channel. The JUNO detector will providea unique facility to address many outstanding crucial questions in particle andastrophysics. It holds the great potential for further advancing our quest tounderstanding the fundamental properties of neutrinos, one of the buildingblocks of our Universe
Detection of the Diffuse Supernova Neutrino Background with JUNO
As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO
Potential of Core-Collapse Supernova Neutrino Detection at JUNO
JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve
Real-time Monitoring for the Next Core-Collapse Supernova in JUNO
Core-collapse supernova (CCSN) is one of the most energetic astrophysical
events in the Universe. The early and prompt detection of neutrinos before
(pre-SN) and during the SN burst is a unique opportunity to realize the
multi-messenger observation of the CCSN events. In this work, we describe the
monitoring concept and present the sensitivity of the system to the pre-SN and
SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is
a 20 kton liquid scintillator detector under construction in South China. The
real-time monitoring system is designed with both the prompt monitors on the
electronic board and online monitors at the data acquisition stage, in order to
ensure both the alert speed and alert coverage of progenitor stars. By assuming
a false alert rate of 1 per year, this monitoring system can be sensitive to
the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos
up to about 370 (360) kpc for a progenitor mass of 30 for the case
of normal (inverted) mass ordering. The pointing ability of the CCSN is
evaluated by using the accumulated event anisotropy of the inverse beta decay
interactions from pre-SN or SN neutrinos, which, along with the early alert,
can play important roles for the followup multi-messenger observations of the
next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure
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