110431759
High-speed charge-to-time converter ASIC for the Super-Kamiokande detector
Abstract A new application-specific integrated circuit (ASIC), the high-speed charge-to-time converter (QTC) IWATSU CLC101, provides three channels, each consisting of preamplifier, discriminator, low-pass filter, and charge integration circuitry, optimized for the waveform of a photomultiplier tube (PMT). This ASIC detects PMT signals using individual built-in discriminators and drives output timing signals whose width represents the integrated charge of the PMT signal. Combined with external input circuits composed of passive elements, the QTC provides full analog signal processing for the detector's PMTs, ready for further processing by time-to-digital converters (TDCs). High-rate ( > 1 MHz ) signal processing is achieved by short-charge-conversion-time and baseline-restoration circuits. Wide-range charge measurements are enabled by offering three gain ranges while maintaining a short cycle time. QTC chip test results show good analog performance, with efficient detection for a single photoelectron signal, four orders of magnitude dynamic range ( 0.3 mV ∼ 3 V ; 0.2 ∼ 2500 pC ), 1% charge linearity, 0.2 pC charge resolution, and 0.1 ns timing resolution. Test results on ambient temperature dependence, channel isolation, and rate dependence also meet specifications.
118598825
A measurement of the cosmic microwave background B-mode polarization power spectrum at sub-degree scales with POLARBEAR
We report a measurement of the B-mode polarization power spectrum in the cosmic microwave background (CMB) using the POLARBEAR experiment in Chile. The faint B-mode polarization signature carries information about the universe's entire history of gravitational structure formation, and the cosmic inflation that may have occurred in the very early universe. Our measurement covers the angular multipole range 500 < ? < 2100 and is based on observations of an effective sky area of 25? with 3.'5 resolution at 150?GHz. On these angular scales, gravitational lensing of the CMB by intervening structure in the universe is expected to be the dominant source of B-mode polarization. Including both systematic and statistical uncertainties, the hypothesis of no B-mode polarization power from gravitational lensing is rejected at 97.2% confidence. The band powers are consistent with the standard cosmological model. Fitting a single lensing amplitude parameter ABB to the measured band powers, , where ABB = 1 is the fiducial WMAP-9 ?CDM value. In this expression, stat refers to the statistical uncertainty, sys to the systematic uncertainty associated with possible biases from the instrument and astrophysical foregrounds, and multi to the calibration uncertainties that have a multiplicative effect on the measured amplitude ABB .
42639050
Development of New Front-End Electronics for Super-Kamiokande
Super-Kamiokande is a ring imaging water Cherenkov detector for astro-particle physics that consists of 50 kton pure water and about 13000 photomultiplier tubes (PMTs). We are planning to upgrade all the front-end electronics in next year. By high speed signal processing electronics, we will record all the hits of all the PMTs without any hardware filtering, aiming observations of much fainter signals of the supernova relic neutrinos, lower energy (~3 MeV) solar neutrinos, neutrino burst from nearby galactic supernova, and so on. The energy resolutions of multi-GeV atmospheric neutrino events will also be improved by the electronics. The new front-end electronics is based on a charge to time converter (QTC) and a multi-hit TDC. TCP/IP based readout channel is implemented to handle large amounts of data. We have developed a custom ASIC QTC and evaluated the characteristics of the chip and the prototypical board; high-speed (1 MHz cycle), high sensitivity for single photo-electron signal, good charge (0.1 pC RMS) and timing (0.3 ns RMS) responses, and wide charge dynamic range (2500 pC). In this paper, the design and the performance of the front-end board are discribed.
25628512
Measurement of the cosmic microwave background polarization lensing power spectrum with the POLARBEAR experiment.
Gravitational lensing due to the large-scale distribution of matter in the cosmos distorts the primordial cosmic microwave background (CMB) and thereby induces new, small-scale B-mode polarization. This signal carries detailed information about the distribution of all the gravitating matter between the observer and CMB last scattering surface. We report the first direct evidence for polarization lensing based on purely CMB information, from using the four-point correlations of even- and odd-parity E- and B-mode polarization mapped over ∼30 square degrees of the sky measured by the POLARBEAR experiment. These data were analyzed using a blind analysis framework and checked for spurious systematic contamination using null tests and simulations. Evidence for the signal of polarization lensing and lensing B modes is found at 4.2σ (stat+sys) significance. The amplitude of matter fluctuations is measured with a precision of 27%, and is found to be consistent with the Lambda cold dark matter cosmological model. This measurement demonstrates a new technique, capable of mapping all gravitating matter in the Universe, sensitive to the sum of neutrino masses, and essential for cleaning the lensing B-mode signal in searches for primordial gravitational waves.
118412548
Mission Design of LiteBIRD
LiteBIRD is a next-generation satellite mission to measure the polarization of the cosmic microwave background (CMB) radiation. On large angular scales the B-mode polarization of the CMB carries the imprint of primordial gravitational waves, and its precise measurement would provide a powerful probe of the epoch of inflation. The goal of LiteBIRD is to achieve a measurement of the characterizing tensor to scalar ratio $$r$$r to an uncertainty of $$\delta r=0.001$$δr=0.001. In order to achieve this goal we will employ a kilo-pixel superconducting detector array on a cryogenically cooled sub-Kelvin focal plane with an optical system at a temperature of 4 K. We are currently considering two detector array options; transition edge sensor (TES) bolometers and microwave kinetic inductance detectors. In this paper we give an overview of LiteBIRD and describe a TES-based polarimeter designed to achieve the target sensitivity of 2 $$\upmu $$μK arcmin over the frequency range 50–320 GHz.
15419917
Gauged N=2 supergravity in nine dimensions and domain wall solutions
Abstract We present massive N=2 supergravity with SO(2)-gauging in nine dimensions by direct construction. A full Lagrangian and transformation rules are fixed, respectively, up to quartic and quadratic fermion terms. Corresponding to the generalized Scherk–Schwarz dimensional reduction utilizing SL(2, R ) symmetry, this theory allows three arbitrary mass parameters m0, m1 and m2 in addition to the minimal gauge coupling g, so that our system has the most general form compared with other results in the past. Unlike ordinary gauged maximal supergravity theories in other dimensions, the scalar potential is positive definite for arbitrary values of the mass parameters. As an application, we also analyze the stability and supersymmetry for 7-brane domain wall solutions for this gauged maximal supergravity, keeping the three mass parameters.
119012576
Deliberations on 11D superspace for the M-theory effective action☆
Abstract In relation to the superspace modifications of 11D supergeometry required to describe the M-theory low-energy effective action, we present an analysis of infinitesimal supergravity fluctuations about the flat superspace limit. Our investigation confirms Howe's interpretation of our previous Bianchi identity analysis. However, the analysis also shows that should 11D supergravity obey the rules of other off-shell supergravity theories, the complete M-theory corrections will necessarily excite our previously anticipated spin-1/2 engineering dimension-1/2 spinor auxiliary multiplet superfield. The analysis of fluctuations yields more evidence that Howe's 1997 theorem is specious when applied to Poincare supergravity or 11D supergravity/M-theory. We end by commenting upon recent advances in this area.
120752257
Calabi-Yau manifold compactification in the heterotic string and N=1 supersymmetry in four dimensions
Abstract We examine whether a torsion-free Calabi-Yau manifold with the SU(3) holonomy group embedded in E 8 ×E 8 satisfies the classical field equations with O(α' 3 ) heterotic string corrections. In general, the torsion-freedom is lost and the exact embedding condition is modified at O(α' 3 ), but the N =1 supersymmetry in four dimensions is still preserved even at O(α' 3 ). Allowing some local field redefinitions, however, we can restore the exact embedding of the SU(3) holonomy into E 8 ×E 8 →E 6 ×SU(3)×E 8 , maintaining also the D =4, N =1 symmetry. Our results are based on the dual (type IB) superspace formulation, which guarantees the on-shell closure of supersymmetry.
15382261
Parity conservation in supersymmetric vector - like theories
We show that parity is conserved in vector-like supersymmetric theories, such as supersymmetric QCD with massive quarks with no cubic couplings among chiral multiplets, based on fermionic path-integrals, originally developed by Vafa and Witten. We also look into the effect of supersymmetric breaking through gluino masses, and see that the parity-conservation is intact also in this case. Our conclusion is valid, when only bosonic parity-breaking observable terms are considered in path-integrals like the original Vafa-Witten formulation.
15767387
Supersymmetric E8(+8)/SO(16) sigma-model coupled to N=1 supergravity in three dimensions
Abstract A three-dimensional simple N =1 supergravity theory with a supersymmetric sigma-model on the coset E 8(+8) / SO (16) is constructed. Both bosons and fermions in the matter multiplets are in the spinorial 128 -representation of SO (16) with the same chirality. Due to their common chirality, this model cannot be obtained from the maximal N =16 supergravity. By introducing an independent vector multiplet, we can also gauge an arbitrary subgroup of SO (16) together with a Chern–Simons term. Similar N =1 supersymmetric σ -models coupled to supergravity are also constructed for the cosets F 4(−20) / SO (9) and SO (8, n )/ SO (8)× SO ( n ).