ICA-Accelerator Calibration Project

The ACCESS accelerator calibration program will compare five different ionization calorimetry concepts for the calorimeter section of the ACCESS instrument. Calibrations will be conducted at the Center for Nuclear Research in Europe (CERN) in 1999 and will initially use a 450 GeV proton beam. Later, heavy ion beams (oxygen, sulfur or lead nuclei), electrons and other proton energies will be utilized. Overall performance of the five full-size instrument concepts are being studied by the individual calorimeter teams in the ACCESS simulation program. The objective of the accelerator test is to provide a performance comparison of the various detectors and techniques and to assess the validity and accuracy of the simulation techniques. The data from the initial accelerator calibration will be compared with detailed simulations of 450 GeV proton primaries which use the ACCESS GEANT programs. Current status of the ACCESS Calibration and Simulation effort are maintained on the respective calorimeter teams' website.

The accelerator version of the ICA module is shown in the attached figures. The main calorimeter section is scaled-down from the ICA design and uses lead plates as the absorbing medium, but with a reduced depth of 15 radiation lengths. Small (0.5mm square) scintillating optical fibers are used throughout the calorimeter to sample the cascades that develop. The output from these fibers will be recorded with image intensified cameras and photo-multiplier tubes. Event triggers will be formed from the photomultiplier tubes and scintillation counters (not shown) upstream and downstream of the calorimeter instrument. A carbon target section is also included in this design. The accelerator calibration program requires a number of simulations for the design and subsequent data analysis. The main elements of this study, summarized from the technical proposal, are listed below.

ICA Accelerator Study elements

1) Compare energy deposition in scintillating fiber layers with results from GEANT simulations.

a) Total energy deposition in all fiber layers (DE )
b) One dimensional transition (shower development) curves of energy deposition in each fiber layer.
c) Shower core (central one or two fibers) transition curves. Pseudo-three-dimensional (3D), and 3D shower fitting will be employed.
d) Lateral ( along fiber plane) cascade development characteristics and fluctuations.

2) Results of 1(a) will be used in later evaluations of the DE method of energy measurement and primary spectrum reconstruction. Results from 1(b)-(d) will be used in evaluations of the first interaction, åEg(1), energy measurement technique.
3) Evaluate cascade measurements at different angles of primary incidence.
4) Study the effect on cascades from different primary interaction positions (depth) in the target and calorimeter.
5) Study the separation of the primary and major secondary interactions with the shower core method (1c).
6) Determine the position resolution for the reconstructed event trajectory (for primary particle identification purposes).
7) Evaluate backscattered characteristics of this calorimeter configuration.
8) Study technical issues: fiber/CCD pixel cross talk, effect of particles outside calorimeter geometry.
9) Compare any measured difference in X and Y fiber layers predicted by simulations.
10) Search for any discernable effects of nuclear interactions on fiber energy deposition and light signal.
11) Build and test data analysis tools required for data reduction.