22684568
MaGe-a Geant4-Based Monte Carlo Application Framework for Low-Background Germanium Experiments
We describe a physics simulation software framework, MaGe, that is based on the Geant4 simulation toolkit. MaGe is used to simulate the response of ultra-low radioactive background detectors to ionizing radiation, specifically the Majorana and Gerda neutrinoless double-beta decay experiments. Majorana and Gerda use high-purity germanium detectors to search for the neutrinoless double-beta decay of 76Ge and MaGe is jointly developed between these two collaborations. The MaGe framework contains the geometry models of common objects, prototypes, test stands and the actual experiments. It also implements customized event generators, Geant4 physics lists and output formats. All of these features are available as class libraries that are typically compiled into a single executable. The user selects the particular experimental setup implementation at run-time via macros. The combination of all these common classes into one framework reduces duplication of efforts, eases comparison between simulated data and experiment and simplifies the addition of new detectors to be simulated. This paper focuses on the software framework, custom event generators and physics lists.
20578469
A Generic Surface Sampler for Monte Carlo Simulations
We present a Monte Carlo algorithm that generates points randomly and uniformly on a set of arbitrary surfaces. The algorithm is completely general and only requires the geometry modeling software to provide the intersection points of an arbitrary line with the surface being sampled. We demonstrate the algorithm using the Geant4 Monte Carlo simulation toolkit. The efficiency of the sampling algorithm is discussed, along with various options in the implementation and example applications.
6698984
The Bulge Globular Cluster NGC 6553: Observations with HST's WFPC2, STIS, and NICMOS
As part of a large HST project to study the formation and evolution of rich star clusters in the Large Magellanic Cloud, we present results for the Galactic bulge metal-rich globular cluster NGC6553. HST observations using WFPC2, NICMOS and STIS were obtained for this cluster. The primarily reason for studying NGC6553 is to allow the possibility to transform our NICMOS and STIS magnitudes directly into stellar masses. This is particularly important for determining the low mass end of the IMF. NGC 6553 was chosen because its metallicity, [Fe/H]$=-0.22\pm 0.05$, is representative of the metallicities
1940549
The GLAST silicon-strip tracking system
The GLAST instrument concept is a gamma-ray pair conversion telescope that uses silicon microstrip detector technology to track the electron-positron pairs resulting from gamma-ray conversions in thin lead foils. A cesium iodide calorimeter following the tracker is used to measure the gamma-ray energy. Silicon strip technology is mature and robust, with an excellent heritage in space science and particle physics. It has many characteristics important for optimal performance of a pair conversion telescope, including high efficiency in thin detector planes, low noise, and excellent resolution and two-track separation. The large size of GLAST and high channel count in the tracker puts demands on the readout technology to operate at very low power, yet with sufficiently low noise occupancy to allow self triggering. A prototype system employing custom-designed ASIC’s has been built and tested that meets the design goal of approximately 200_W per channel power consumption with a noise occupancy of less than one...
115852024
Measurement of the quantum efficiency of TMAE and TEA from threshold to 120 nm
Several existing and planned high energy physics experiments incorporate detectors which use either TMAE (tetrakis-dimethylaminoethylene) or TEA (triethylamine) as their photosensitive agent. Understanding the operation of these devices requires knowledge of the absolute photoionization quantum efficiencies and absorption lengths of TMAE and TEA. In an experiment performed at the National Synchrotron Light source at Brookhaven National Laboratory, we have measured these parameters from 120 nm to 280 nm. The quantum efficiencies were normalized to the known photoionization yields of benzene and cis-2-butene. The results of these measurements and details of the experiment are presented in this paper.
122618630
Signal processing in the front-end electronics of BaBar vertex detector
Abstract The microstrip vertex detector in BaBar experiment will be read out by a purposely designed front-end chip. The chip performs amplification and analog-to-digital conversion to retain the information of the charge induced on the readout strips. It stores the digital data during the trigger latency time and associates the incoming trigger with the relevant hit data. Data are buffered and sent off in sparsified form when a readout command is received. The present paper discusses the signal processing performed by the chip.
120263601
A Time-differencing Technique for Detecting Radio-quiet Gamma-Ray Pulsars
Detecting periodicity from a γ-ray pulsar is exceedingly difficult without prior knowledge of its pulsation frequency and frequency derivative. The low fluxes attainable in the gamma-ray band mandate very long exposures, making the direct application of Fourier analysis methods computationally prohibitive. Accumulation of phase shifts induced by significant frequency derivatives requires that the large Fourier transforms be repeated over many trials, and occasional "glitches" in the pulsar rotation compound the difficulties. By analyzing the differences of photon arrival times rather than the time series itself, we show that we can maintain good sensitivity while greatly reducing the effects of frequency derivatives and glitches. To demonstrate its power, we use simulated data to compare our time-differencing algorithm with two Fourier methods used in previous searches for radio-quiet γ-ray pulsars.