119726391
Isospin mixing of the 1+ doublet in 12C determined by low-energy pion scattering☆
With the Low Energy Pion Spectrometer (LEPS) at PSI the inelastic scattering of 50 MeV positive and negative pions to the 1+ excitations at 12.71 MeV (T = 0) and 15.11 MeV (T = 1) in 12C has been measured in the angular range 35°−105°. The angular distributions are in good agreement with impulse approximation calcculations. From the double ratio of the 1+ cross sections for π+ and π− scattering an isospin mixing matrix element of H01 = 157 ± 35 keV is derived. In contrast to a previous study of this reaction these results do not question the validity of the impulse approximation at low energies.
111114972
Commissioning Experience with the ATLAS Level-1 Calorimeter Trigger System
The ATLAS Level-1 Calorimeter Trigger is one of the main elements of the first stage of event selection for the ATLAS experiment at the LHC. The input stage consists of a mixed analogue/digital component taking trigger sums from the ATLAS calorimeters. The trigger logic is performed in a digital, pipelined system with several stages of processing, largely based on FPGAs, which perform programmable algorithms in parallel with a fixed latency to process about 300 Gbyte/s of input data. The real-time output consists of counts of different types of physics objects and energy sums. The production of final modules started in 2006, and installation of these modules and the necessary infrastructure at ATLAS has been underway for some time, with the intention of having a full system in situ during 2007, before first collisions at the LHC. The first experiences of commissioning and running the full scale system will be presented, along with results from integration tests performed with the upstream calorimeters, and the downstream trigger and data flow systems.
122279281
The triumf low energy pion spectrometer and channel
Abstract A low energy pion spectrometer has been developed for use with the TRIUMF M13 pion channel. The combined channel and spectrometer resolution is presently 1.1. MeV at T = 50 MeV. This is limited by the amount of gas and detector material in the spectrometer in addition to the inherent resolution of the channel. Improvements to both the spectrometer and channel are discussed.
61376443
Prototype cluster processor module for the ATLAS level-1 calorimeter trigger
The Level-1 Calorimeter Trigger consists of a Preprocessor, a Cluster Processor (CP), and a Jet/Energy -sum Processor (JEP). The CP and JEP receive digitised triggertower data from the Preprocessor and produce trigger multiplicity and region-of-interest (RoI) information. The CP Modules (CPM) are designed to find isolated electron/photon and hadron/tau clusters in overlapping windows of trigger towers. Each pipelined CPM processes a total of 280 trigger towers of 8-bit length at a clock speed of 40 MHz. This huge I/O rate is achieved by serialising and multiplexing the input data. Large FPGA devices have been used to retrieve data and perform the cluster-finding algorithm. A full-specification prototype module has been built and tested, and first results will be presented.
27359669
The ATLAS level-1 calorimeter trigger architecture
The architecture of the ATLAS Level-1 Calorimeter Trigger system (L1Calo) is presented. Common approaches have been adopted for data distribution, result merging, readout, and slow control across the three different subsystems. A significant amount of common hardware is utilized, yielding substantial savings in cost, spares, and development effort. A custom, high-density backplane has been developed with data paths suitable for both the em//spl tau/ cluster processor (CP) and jet/energy-summation processor (JEP) subsystems. Common modules also provide interfaces to VME, CANbus and the LHC timing, trigger and control system (TTC). A common data merger module (CMM) uses field-programmable gate arrays (FPGAs) with multiple configurations for summing electron/photon and /spl tau//hadron cluster multiplicities, jet multiplicities, or total and missing transverse energy. The CMM performs both crate- and system-level merging. A common, FPGA-based readout driver (ROD) is used by all of the subsystems to send input, intermediate and output data to the data acquisition (DAQ) system, and region-of-interest (RoI) data to the level-2 triggers. Extensive use of FPGAs throughout the system makes the trigger flexible and upgradable, and several architectural choices have been made to reduce the number of intercrate links and make the hardware more robust.
15246775
Prototype Readout Module for the ATLAS Level-1 Calorimeter Trigger Processors
The level-1 calorimeter trigger consists of three subsystems, namely the Preprocessor, electron/photon and tau/hadron Cluster Processor (CP), and Jet/Energy-sum Processor (JEP). The CP and JEP will receive digitised calorimeter trigger-tower data from the Preprocessor and will provide trigger multiplicity information to the Central Trigger Processor and region-of-interest (RoI) information for the level-2 trigger. It will also provide intermediate results to the data acquisition (DAQ) system for monitoring and diagnostic purposes. This paper will outline a readout system based on FPGA technology, providing a common solution for both DAQ readout and RoI readout for the CP and the JEP. Results of building a prototype readout driver (ROD) module will be presented, together with results of tests on its integration with level-2 and DAQ modules.
122598679
Measurement of the polarization parameter in K$sup +$p elastic scattering
Full angular distributions of the polarization parameter in elastic ${K}^{+}p$ scattering at 1.37, 1.45, 1.60, 1.71, 1.80, 1.89, 2.11, and 2.31 GeV/c are presented. These data were obtained in an experiment at the Zero Gradient Synchrotron using a polarized proton target with arrays of scintillation and \ifmmode \check{C}\else \v{C}\fi{}erenkov counters to detect the scattered particles.
119923394
A triangular tube proportional wire chamber system
Abstract We report on the characteristics of the proportional tube chamber system which has been constructed for muon identification in the PEP-4 experiment at SLAC. The mechanical and electrical properties of the extruded aluminum triangular tubes allow these detectors to be used as crude drift chambers.
122601142
SVX', the new CDF silicon vertex detector
Abstract The Collider Detector at Fermilab (CDF) radiation hardened silicon vertex detector (SVX') is described. The new detector has several improvements over its predecessor such as better signal to noise and higher efficiency. It is expected to have a radiation tolerance in excess of 1 Mrad. It has been taking data for several months and some preliminary results are shown.
9876488
An alignment method for the mark II silicon strip vertex detector using an X-ray beam
Abstract Silicon strip vertex detector consisting of 36 independent detector modules is being constructed for use in the Mark II detector at a SLAC Linear Collider. This paper describes a method for determining the relative alignment of the modules to a precision better than the 5 μm intrinsic resolution of the detectors. The basic procedure involves moving the vertex detector by known amounts through a fixed, collimated X-ray beam, and using the beam position reconstructed from the detected signals to determine the relative positions and orientations of the modules. Results from tests of the method on a subset of detectors are presented.
123486645
A Study of the detailed characteristics of hadron - nucleus collisions using the Fermilab hybrid spectrometer