Thermoelastic study of nanolayered structures using time-resolved x-ray diffraction at high repetition rate

We investigate the thermoelastic response of a nanolayered sample composed of a metallic SrRuO3 (SRO) electrode sandwiched between a ferroelectric Pb(Zr0.2Ti0.8)O3 (PZT) film with negative thermal expansion and a SrTiO3 substrate. SRO is rapidly heated by fs-laser pulses with 208 kHz repetition rate. Diffraction of x-ray pulses derived from a synchrotron measures the transient out-of-plane lattice constant c of all three materials simultaneously from 120 ps to 5 mus with a relative accuracy up to Delta c/c = 10^-6. The in-plane propagation of sound is essential for understanding the delayed out of plane expansion.Comment: 5 pages, 3 figure

Recent progress of GaAsP HPD development for the MAGIC telescope project

Today the Hybrid Photon Detector (HPD) is one of the few low light level (LLL) sensors that can provide an excellent single and multiple photoelectron (ph.e.) amplitude resolution. The recently developed HPDs for the MAGIC telescope project with a GaAsP photocathode, namely the R9792U-40, provide a peak quantum efficiency (QE) of more than 50% and a pulse width of ~2 nsec. In addition, the afterpulsing rate of these tubes is very low compared to that of conventional photomultiplier tubes (PMTs), i.e. the value is ~300 times lower. Photocathode aging measurements showed life time of more than 10 years under standard operating conditions of the Cherenkov Telescopes. Here we want to report on the recent progress with the above mentioned HPDs.Comment: Contribution to the 30th ICRC, Merida Mexico, July 2007 on behalf of the MAGIC Collaboratio

Study of the performance and capability of the new ultra-fast 2 GSample/s FADC data acquisition system of the MAGIC telescope

In February 2007 the MAGIC Air Cherenkov Telescope for gamma-ray astronomy was fully upgraded with an ultra fast 2 GSamples/s digitization system. Since the Cherenkov light flashes are very short, a fast readout can minimize the influence of the background from the light of the night sky. Also, the time structure of the event is an additional parameter to reduce the background from unwanted hadronic showers. An overview of the performance of the new system and its impact on the sensitivity of the MAGIC instrument will be presented.Comment: Contribution to the 30th ICRC, Merida Mexico, July 2007 on behalf of the MAGIC Collaboratio

Long term monitoring of bright TeV Blazars with the MAGIC telescope

The MAGIC telescope has performed long term monitoring observations of the bright TeV Blazars Mrk421, Mrk501 and 1ES1959+650. Up to 40 observations, 30 to 60 minutes each have been performed for each source evenly distributed over the observable period of the year. The sensitivity of MAGIC is sufficient to establish a flux level of 25% of the Crab flux for each measurement. These observations are well suited to trigger multiwavelength ToO observations and the overall collected data allow an unbiased study of the flaring statistics of the observed AGNs.Comment: 4 pages, 4 figures, to appear in the proceedings of the 30th International Cosmic Ray Conference, Merida, July 200

UDKM1DSIM A simulation toolkit for 1D ultrafast dynamics in condensed matter

The UDKM1DSIM toolbox is a collection of MATLAB MathWorks Inc. classes and routines to simulate the structural dynamics and the according X ray diffraction response in one dimensional crystalline sample structures upon an arbitrary time dependent external stimulus, e.g. an ultrashort laser pulse. The toolbox provides the capabilities to define arbitrary layered structures on the atomic level including a rich database of corresponding element specific physical properties. The excitation of ultrafast dynamics is represented by an N temperature model which is commonly applied for ultrafast optical excitations. Structural dynamics due to thermal stress are calculated by a linear chain model of masses and springs. The resulting X ray diffraction response is computed by dynamical X ray theory. The UDKM1DSIM toolbox is highly modular and allows for introducing user defined results at any step in the simulation procedur

Development of HPD Clusters for MAGIC-II

MAGIC-II is the second imaging atmospheric Cherenkov telescope of the MAGIC observatory, which has recently been inaugurated on Canary island of La Palma. We are currently developing a new camera based on clusters of hybrid photon detectors (HPD) for the upgrade of MAGIC-II. The photon detectors feature a GaAsP photocathode and an avalanche diode as electron bombarded anodes with internal gain, and were supplied by Hamamatsu Photonics K.K. (R9792U-40). The HPD camera with high quantum efficiency will increase the MAGIC-II sensitivity and lower the energy threshold. The basic performance of the HPDs has been measured and a prototype of an HPD cluster has been developed to be mounted on MAGIC-II. Here we report on the status of the HPD cluster and the project of eventually using HPD clusters in the central area of the MAGIC-II camera.Comment: Contribution to the 31st ICRC, Lodz, Poland, July 200

Progress in Monte Carlo design and optimization of the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) will be an instrument covering a wide energy range in very-high-energy (VHE) gamma rays. CTA will include several types of telescopes, in order to optimize the performance over the whole energy range. Both large-scale Monte Carlo (MC) simulations of CTA super-sets (including many different possible CTA layouts as sub-sets) and smaller-scale simulations dedicated to individual aspects were carried out and are on-going. We summarize results of the prior round of large-scale simulations, show where the design has now evolved beyond the conservative assumptions of the prior round and present first results from the on-going new round of MC simulations.Comment: 4 pages, 5 figures. In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.223