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Register a new userA Procedure to Calibrate a Multi-Modular Telescope
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1995
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A procedure has been developed for the charge, mass and energy calibration of ions produced in nuclear heavy ion reactions. The charge and mass identification are based on a $Delta$E-E technique. A computer code determines the conversion from ADC channels into energy values, atomic number and mass of the detected fragments by comparing with energy loss calculations through a minimization routine. The procedure does not need prior measurements with beams of known energy and charge. An application of this technique to the calibration of the MULTICS apparatus is described.
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In this contribution, a design of a synthetic calibration genetic circuit to characterize the relative strength of different sensing promoters is proposed and its specifications and performance are analyzed via an effective mathematical model. Our calibrator device possesses certain novel and useful features like modularity (and thus the possibility of being used in many different biological contexts), simplicity, being based on a single cell, high sensitivity and fast response. To uncover the critical model parameters and the corresponding parameter domain at which the calibrator performance will be optimal, a sensitivity analysis of the model parameters was carried out over a given range of sensing protein concentrations (acting as input). Our analysis suggests that the half saturation constants for repression, sensing and difference in binding cooperativity (Hill coefficients) for repression are the key to the performance of the proposed device. They furthermore are determinant for the sensing speed of the device, showing that it is possible to produce detectable differences in the repression protein concentrations and in turn in the corresponding fluorescence in less than two hours. This analysis paves the way for the design, experimental construction and validation of a new family of functional genetic circuits for the purpose of calibrating promoters.
The Cherenkov Telescope Array is a project that aims to exploring the highest energy region of electromagnetic spectrum. Two arrays, one for each hemisphere, will cover the full sky in a range from few tens of GeV to hundreds of TeV improving the sensitivity and angular resolution of the present operating arrays. A prototype of the Large Size Telescope (LST) for the study of gamma ray astronomy above some tens of GeV will be installed at the Canary Island of La Palma in 2016. The LST camera, made by an array of photomultipliers (PMTs), requires an accurate and systematic calibration over a wide dynamic range. In this contribution, we present an optical calibration system made by a 355 nm wavelength laser with 400 ps pulse width, 1 muJ output energy, up to 4k Hz repetition rate and a set of neutral density filters to obtain a wide range of photon intensities, up to 1000 photoelectrons/PMT, to be sent to the camera plane 28 m away. The number of photons after the diffuser of the calibration box, located in the center of the reflective plane, is monitored by a photodiode. The stability of the laser and the ambient parameters inside this calibration box are checked by a multi-task processor and a trigger signal is sent to the camera data acquisition system. The box frame is designed with special attention to obtain a robust device with stable optical and mechanical features.
A Large Size air Cherenkov Telescope (LST) prototype, proposed for the Cherenkov Telescope Array (CTA), is under construction at the Canary Island of La Palma (Spain) this year. The LST camera, which comprises an array of about 500 photomultipliers (PMTs), requires a precise and regular calibration over a large dynamic range, up to $10^3$ photo-electrons (pes), for each PMT. We present a system built to provide the optical calibration of the camera consisting of a pulsed laser (355 nm wavelength, 400 ps pulse width), a set of filters to guarantee a large dynamic range of photons on the sensors, and a diffusing sphere to uniformly spread the laser light, with flat fielding within 3%, over the camera focal plane 28 m away. The prototype of the system developed at INFN is hermetically closed and filled with dry air to make the system completely isolated from the external environment. In the paper we present the results of the tests for the evaluation of the photon density at the camera plane, the system isolation from the environment, and the shape of the signal as detected by the PMTs. The description of the communication of the system with the rest of detector is also given.
We have developed a multi-objective optimization (MOO) procedure to construct modified-embedded-atom-method (MEAM) potentials with minimal manual fitting. This procedure has been applied successfully to develop a new MEAM potential for magnesium. The MOO procedure is designed to optimally reproduce multiple target values that consist of important materials properties obtained from experiments and first-principles calculations based on density-functional theory (DFT). The optimized target quantities include elastic constants, cohesive energies, surface energies, vacancy formation energies, and the forces on atoms in a variety of structures. The accuracy of the new potential is assessed by computing several material properties of Mg and comparing them with those obtained from other potentials previously published. We found that the present MEAM potential yields a significantly better overall agreement with DFT calculations and experiments.
This is a preliminary version of a formal proposal by the 3M collaboration to construct a megaton, modular, multipurpose (3M) neutrino detector for a program of experiments in neutrino physics. The detector components will be located in chambers approximately 7000 ft below the Earths surface in the Homestake Mine at Lead, South Dakota, to carry out experiments on neutrino oscillations directed toward the principal experimental goal of the program, viz., the issue of CP-invariance violation in the lepton sector of elementary particles, an issue that has been the subject of study in the quark sector for several decades. The principal physics goal of this program also requires a moderately intense neutrino beam from an accelerator located a long distance from the detector array, such as the 2540 km distance of BNL from Homestake. The construction plan for that neutrino beam is at http://nwg.phy.bnl.gov/. Other experimental searches that do not require the accelerator-generated beam can be carried out with the 3M detector independently of and at the same time as the neutrino oscillation and CP-invariance violation measurements are in progress. They are searches for Proton Decay, UHE Neutrinos, and Supernovae Neutrinos.
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