121380547
A highly sensitive optical detector for use in deep underwater
Abstract We have developed an optical detector module for use in deep underwater experiments that will search for high-energy neutrinos from cosmic rays and astronomical sources. This module is sensitive to single photons, is operable under high pressure, functions automatically and is remotely controlled. The optical module is based on a 15 in. diameter photomultiplier tube (PMT), with control and read-out electronics mounted inside a 17 in. diameter glass pressure housing. The photomultiplier output signal is converted into two optical pulses by the electronics, one giving the hit time and time-over-threshold of the PMT output pulse and the other giving the charge-integrated PMT signal. Information on the arrival time and intensity of light can be extracted from these pulses. The time jitter of the optical modules is ∼6 and ∼2 ns at FWHM for one photoelectron and ∼100 photoelectrons, respectively. The unit requires 10 W power delivered at 48 V DC on a line with superposed bidirectional control signals. Fast output is uni-directional on a multi-mode fiber optic link to a remote time digitizer. The module has been successfully tested and calibrated in the laboratory, and several have briefly operated in the deep ocean.
122317578
Recent Progress in the Development of a Monolithic Active Pixel Detector for a B-Factory
Monolithic Active Pixel Sensors (MAPS) may become the building blocks of vertex detectors at future high luminosity e + e colliders. Requiring an active layer only a few tens of microns thick, MAPS can be thinned to ∼ 50µm, which reduces the multiple scattering of primary particles. Deep sub-micron CMOS processes allow for small pixel size, needed for adequate single point resolution and low occupancy at a Super B factory. Major concerns with MAPS are readout speed and signal stability for large pixel arrays. Laser bench test results of a full size prototype (CAP3) with 118,784 readout pixels and a 5-deep correlated double sampling pipeline are presented. Lessons learned are applied to a design iteration and investigation of two new digital readout sensor designs, all included in the CAP4 prototype chip.
6053322
Development of a B-factory monolithic active pixel detector-the continuous-acquisition pixel prototypes
Future vertex detection at an upgraded KEK-B factory, currently the highest luminosity collider in the world, will require a detector technology capable of withstanding the increased track density and the larger radiation exposure. Near the beam pipe, the current silicon strip detectors have projected occupancies in excess of 100%. Advances in monolithic active-pixel sensors (MAPS) look very promising to address this problem. These devices are also quite attractive due to the possibility of making them very thin-essential for improved tracking and vertexing in the low-momenta environment of a B-factory. In the context of the Belle vertex detector upgrade, the major obstacles to realizing such a device have been concerns about radiation hardness and readout speed. Two prototypes implemented in the TSMC 0.35 /spl mu/m process have been developed to address these issues. Denoted the continuous-acquisition pixel (CAP), the two variants of this architecture are distinguished in that CAP2 includes an eight-deep sampling pipeline within each 22.5 /spl mu/m/sup 2/ pixel. Experience with this deep submicron process indicates tolerable threshold voltage shifts for ionizing radiation in excess of 20 Mrad. In order to maintain low occupancy and insensitivity to radiation-induced increased leakage current, correlated double sampling with a 10 /spl mu/s frame period is needed. Device description, hit resolution, and irradiation results are presented.
6730281
Detection of Ultra High Energy Neutrinos via Coherent Radio Emission
Since the 1960’s it has been predicted that cosmic ray protons of the highest energies must produce corresponding high energy neutrinos due to collisions with the cosmic microwave background. Both the origin and mechanism for production of these protons remain a mystery. Detection of the neutrinos, which remain unaffected by poorly-constrained galactic and inter-galactic magnetic fields, provide a useful new astronomical observation window. Moreover, Askyaryan pointed out that detection of these neutrinos via induced showers in solid, radio transparent media, would be observable at large distances due to the coherenence of the radio emission. However, more than four decades later none of these predicted events have been observed. This has been due in part to the need for enormous target volumes and cost-effective ways to instrument them. Without being able to either trigger or record such transient signals in an efficient manner, detection remains elusive. We present a high-performance, cost-effective and low-power solution to this detection problem. Low-power is needed for balloon-borne detection, and this work was done in the context of the Antarctic Impulsive Transient Antenna (ANITA) high altitude balloon project. However the compact and low-cost nature of the sampling ASIC and triggering technology opens opportunities for viable, large-scale terrestrial radio neutrino detector arrays.
120391197
The Status of Hawaii Askaryan Salt Radi Array (HASRA) experiment
The exploration of GZK neutrinos through their interactions with matter via produced radio signals requires highly homogeneous material with small attenuation for radio frequencies. Rock salt in some salt dome formations provide dielectric material with great potential to host a large scale (100 km3) water-equivalent ultra-high energy neutrino detector The Hawaii Askaryan in Salt Radio Array (HASRA) detector was built as a testbed for exploration of coherent radio Cherenkov emission in salt from interaction of cosmic ray induced cascades. We report results of 1 year of measurements of Askaryan effect with HASRA detector. Peformance of the detector its sensitivity and analysis of a newest data set will be presented.
119180543
Application of Time Projection Chambers with GEMs and Pixels to WIMP Searches and Fast Neutron Detection
Abstract We present work on the detection of neutral particles via nuclear recoils in gas-ﬁlled Time Projection Chambers (TPCs). We employ Gas Electron Multipliers (GEMs) to amplify the signal and silicon pixel electronics to detect the avalanche charge. These technologies allow ionization in the target gas to be detected with low noise, improved position and time resolution, and high efficiency. We review experimental results obtained in previous years, and report on ongoing simulation studies and construction of the ﬁrst prototype at the University of Hawaii. We also present prospects of using such detectors to perform direction-sensitive searches for WIMP dark matter and fast neutron from ﬁssionable material.
119549050
ELECTRON SCATTERING FROM DEFORMED NUCLEI.
A general phenomenological theory is developed for the calculation of both elastic and inelastic transverse and longitudinal form factors for electron scattering from nuclei whose surfaces are deformed according to the expression $R+{(4\ensuremath{\pi})}^{\frac{1}{2}}{\ensuremath{\Sigma}}_{\mathrm{lm}}{\stackrel{^}{a}}_{\mathrm{lm}}{Y}_{\mathrm{lm}}(\stackrel{^}{\mathcal{r}})$. Here, the ${\stackrel{^}{a}}_{\mathrm{lm}}$ are operators in the nuclear Hilbert space, whose detailed dynamical character is left unspecified. The effects of deformation on the scattering, to any desired accuracy, are contained in reduced matrix elements of tensor products of the ${\stackrel{^}{a}}_{\mathrm{lm}}$. These are then treated as phenomenological parameters whose values are to be fixed from an analysis of the scattering cross sections, particularly at high momentum transfer. All the static and transition multipole moments of the nucleus are thereby determined, at least in principle. The Helm model and its generalization to transverse scattering are obtained in the small-deformation limit. The theory is used to analyze the Coulomb elastic and inelastic (to the 1.3-MeV ${\frac{3}{2}}^{+}$ level) scattering of electrons from $^{59}\mathrm{Co}$, as well as the magnetic elastic and inelastic scattering from $^{10}\mathrm{B}$. It is shown that the contribution of the deformation to elastic monopole scattering may be interpreted as due to an effective, oscillatory, spherically symmetric "modulating-charge" distribution, superimposed upon the more usual smeared uniform distribution. It is therefore suggested that the oscillations in the charge distribution which seem to be required in order to fit the high-energy elastic scattering from $^{40}\mathrm{Ca}$ and other nuclei may be due to deformations.
122327020
Dispersion corrections to elastic electron scattering by 16O and 12C
Abstract Longitudinal dispersion corrections to elastic electron scattering from 16 O and 12 C are calculated using oscillator wave functions and closure approximation. Near the first diffraction minimum, the contributions from the Pauli, COM and self-correlations almost cancel. The correction increases away from the minimum.
121684553
EFFECT OF DYNAMICAL DEFORMATION IN ELASTIC ELECTRON SCATTERING ON THE CHARGE DISTRIBUTIONS OF THE CALCIUM ISOTOPES.
The presence of dynamical deformations in the ground-state charge distributions of the calcium isotopes provides a basis for understanding two well-known but very different effects observed in elastic electron scattering from these isotopes.
120797993
Comment on precise single-scattering optical-potential fit to 1 GeV p-$sup 4$He elastic scattering