37649879
LAr TPC Electronics CMOS Lifetime at 300 K and 77 K and Reliability Under Thermal Cycling
A study of hot-carrier effects (HCE) on the 180-nm CMOS device lifetime has been performed at 300 K and 77 K for Liquid Argon Time Projection Chamber (LAr TPC). Two different measurements were used: accelerated lifetime measurement under severe electric field stress by the drain-source voltage Vds, and a separate measurement of the substrate current as a function of 1/Vds. The former verifies the canonical very steep slope of the inverse relation between the lifetime and the substrate current, and the latter confirms that below a certain value of Vds a lifetime margin of several orders of magnitude can be achieved for the cold electronics TPC readout. The low power ASIC design for LAr TPC falls naturally into this domain, where hot-electron effects are negligible. Lifetime of digital circuits (ac operation) is extended by the inverse duty factor 1/(fclockteff) compared to dc operation. This factor is large (> 100) for deep submicron technology and clock frequency needed for TPC readout. As an additional margin, Vds may be reduced by ~ 10%. Extremely low failure rate (incidence) in previous large experiments demonstrates that surface mount circuit board technology withstands very well even multiple abrupt immersion in liquid nitrogen applied in board testing, and that the total failure incidence in continuous operation over time is very low.
109836098
Design and characterization of the VMM1 ASIC for micropattern gas detectors
Abstract Measurements of the first prototype VMM1 ASIC designed at Brookhaven National Laboratory in 130 nm CMOS and fabricated in spring 2012 are presented. The 64-channel ASIC features a novel design for use with several types of micropattern gas detectors. The data driven system measures peak amplitude and timing information in tracking mode including sub-threshold neighbors and first channel hit address in trigger mode. Several programmable gain and integration times allows the flexibility to work with Micromegas, Thin Gap Chambers (TGCs), and Gas Electron Multiplier (GEM) detectors. The IC design and features are presented along with measurements characterizing the performance of the VMM1 such as noise, linearity of the response, time walk, and calibration range.
119352619
Decomposition of SU(N) connection and effective theory of SU(N) QCD
We give a general decomposition of SU(N) connection and derive a generalized Skyrme-Faddeev action as the effective action of SU(N) QCD in the Low energy limit. The result is obtained by separating the topological degrees which describes the non-Abelian monopoles from the dynamical degree of gauge potential, and integrating all the dynamical degrees of SU(N) QCD. (C) 2000 Published by Elsevier Science B.V.
16179887
First calculation of cosmic-ray muon spallation backgrounds for MeV astrophysical neutrino signals in Super-Kamiokande
signals is much larger than the signal rates for kinetic energies of about 6 { 18 MeV. Surprisingly, there is no published calculation of the production and properties of these backgrounds in water, though there are such studies for scintillator. Using the simulation code FLUKA and theoretical insights, we detail how muons lose energy in water, produce secondary particles, how and where these secondaries produce isotopes, and the properties of the backgrounds from their decays. We reproduce Super-Kamiokande measurements of the total background to within a factor of 2, which is good given that the isotope yields vary by orders of magnitude and that some details of the experiment are unknown to us at this level. Our results break aggregate data into component isotopes, reveal their separate production mechanisms, and preserve correlations between them. We outline how to implement more eective background rejection techniques using this information. Reducing backgrounds in solar and DSNB studies by even a factor of a few could help lead to important new discoveries.
120721773
PRELIMINARY COMMISSIONING OF SUPERCONDUCTING MAGNETS AND CRYOGENIC SYSTEM OF BEPC II
A helium cryogenic system with cooling capacity of 1 kW at 4.5 K was set up at Institute of High Energy Physics, Chinese Academy of Sciences, Beijing. This helium refrigerating system is dedicated for the cooling of two superconducting radio frequency (SRF) cavities, two interaction region superconducting collision quadrupole (SCQ) magnets, a detector superconducting solenoid magnet (SSM), which are the key items of the upgrade project of Beijing Electron-Positron Collider (BEPC II). Commissioning with the detector and SCQ magnets was carried out, which will be introduced in this paper. The cryogenic system shows very robust as SSM quench. This paper presents the overall status and some test results of superconducting and cryogenic system.
189809274
Dirac structure of quark-hadron vertex in Bethe-Salpeter wave function under the framework covariant instantaneous ansatz
In the framework of covariant instantaneous ansatz, the general form of the quark-hadron vertex of certain kind of mesons is provided; how to arrange the Dirac covariants of the complete set by the power counting rule is discussed. Employing the leading order Dirac covariants for vector and pseudoscalar mesons, their decay constants are calculated. This proceeding paper is complementary to our other two previous papers, emphasizing on some conceptual discussions. The strong interaction is special for its basic degree of freedoms are confined in hadrons, preventing the measurement of the “really-free” quanta, i.e., quarks and gluons in quantum chromodynamics (QCD). Hence, a description for the asymptotic states, the hadrons, in the strong interactions/collisions, with the language of the basic quanta/fields, quarks, and gluons, is a necessary but challenging task. In the framework of relativistic quantum field theory, at least one “standard” way to describe bound states, i.e., the Bethe-Salpeter wave function (BSW), which is the solution of the Bethe-Salpeter integral equation (BSE), seems available. Through an extensive employment of various techniques in the quantum field theory, such as the DysonSchwinger Equations, one may expect to know the movement of the quarks and gluons in hadrons, and to calculate various kinds of interactions/collisions in various energy scales with such knowledge. This is one of the most important purposes of studying the hadron structure. However, a full understanding of the physical picture of the BSW and a satisfactory way to solve the BES in QCD are still beyond approach. Even, one is not able to give the “rigorous” form of the kernel of the BSE without practical non-perturbative techniques in QCD. More specifically, one has a very powerful picture/tool in high energy hadronic interactions, i.e., the perturbative QCD inspired parton model, but how to approach this parton picture starting from low energy BSW of hadron is an open question. At the same time, the standard factorization scheme is often facing danger in various special processes [1, 2]. So it is very much justified to put more labour on the study of BSW/BSE, especially their
54545936
Multirefringence phenomena in nonlinear electrodynamics
Universite´ de Nice Sophia Antipolis, 06103 Nice Cedex 2, Franceand Dipartimento di Fisica and ICRA, Sapienza Universita` di Roma, I-00185 Rome, Italy(Received 19 April 2013; published 13 September 2013)Wave propagation in nonlinear theories of the electromagnetism described by Lagrangian densitiesdependent upon its two local invariants LðF;GÞ is revisited. On the light of the recent ﬁndings inmetamaterials, it is here shown that trirefringence is also a possible phenomenon to occur in the realm ofsuch nonlinear theories. A speciﬁc model exhibiting this effect is investigated in terms of both phase andgroup velocities. It is claimed that wave propagation in some well known nonlinear models for spin-oneﬁelds, like QED and QCD in certain regimes, may exhibit trirefringence.