Wolfgang Lohmann

Forward instrumentation for ILC detectors

Two special calorimeters are foreseen for the instrumentation of the very forward region of the ILC detector, a luminometer designed to measure the rate of low angle Bhabha scattering events with a precision better than 10?3 and a low polar angle calorimeter, adjacent to the beam-pipe. The latter will be hit by a large amount of beamstrahlung remnants. The amount and shape of these depositions will allow a fast luminosity estimate and the determination of beam parameters. The sensors of this calorimeter must be radiation hard. Both devices will improve the hermeticity of the detector in the search for new particles. Finely segmented and very compact calorimeters will match the requirements. Due to the high occupancy fast front-end electronics is needed. The design of the calorimeters developed and optimised with Monte Carlo simulations is presented. Sensors and readout electronics ASICs have been designed and prototypes are available. Results on the performance of these major components are summarised.

Instrumentation of the very forward region of a linear collider detector

The very forward region of a linear collider detector is a particularly challenging area for instrumentation. For the TESLA project a luminometer (LAT) at small polar angles is foreseen to perform a high precision (O(10/sup -4/)) luminosity measurement, requiring the control of the systematics on the corresponding level. Monte Carlo simulations to optimize the shape and the structure of the calorimeter are presented. A second calorimeter (LCAL) is positioned just adjacent to the beampipe. Into this device a large amount of bremsstrahlung remnants, several ten TeV per bunch crossing, is scattered, resulting in a radiation dose of about 10 MGy per year. The distribution of the bremsstrahlung has to be measured in order to assist in the tuning of the beams at the final focus. Furthermore, single hard electrons have to be measured, or at least vetoed. The latter is important, since events with high energetic electrons near the beampipe are a serious background in many search channels with missing energy and momentum. Monte Carlo simulations for a heavy crystal calorimeter and a diamond/tungsten sandwich structures are presented and compared. First results on sensor tests are given.

Polycrystalline CVD Diamonds for the Beam Calorimeter of the ILC

Polycrystalline artificial diamond produced by chemical vapor deposition (pCVD) is a possible sensor material for the beam calorimeter of the ILC. The requirements are linearity over a large range of flux and radiation hardness against a total ionizing dose of several MGy per year of operation. A hadron test beam at the CERN PS was used to study the linearity of the response of pCVD sensors. An electron test beam at the S-DALINAC was used to measure the charge collection distance (CCD) as a function of the absorbed dose up to several MGy. Current-voltage characteristics of these sensors were measured before and after the irradiation as well as the dependence of the CCD on the applied electric field before and after the irradiation.

Prospects for the measurement of the Higgs boson masswith a linear e + e - collider

Abstract.The potential of a linear e + e- collider operated at a centre-of-mass energy of 350 GeV is studied for the measurement of the Higgs boson mass. An integrated luminosity of 500 fb-1 is assumed. For Higgs boson masses of 120, 150 and 180 GeV the uncertainty on the Higgs boson mass measurement is estimated to be 40, 65 and 70 MeV, respectively. The effects of beam related systematics, namely a bias in the beam energy measurement, the beam energy spread and the luminosity spectrum due to beamstrahlung, on the precision of the Higgs boson mass measurement are investigated. In order to keep the systematic uncertainty on the Higgs boson mass well below the level of the statistical error, the beam energy measurement must be controlled with a relative precision better than 10-4.

Performance of fully instrumented detector planes of the forward calorimeter of a Linear Collider detector

Detector-plane prototypes of the very forward calorimetry of a future detector at an e+e- collider have been built and their performance was measured in an electron beam. The detector plane comprises silicon or GaAs pad sensors, dedicated front-end and ADC ASICs, and an FPGA for data concentration. Measurements of the signal-to-noise ratio and the response as a function of the position of the sensor are presented. A deconvolution method is successfully applied, and a comparison of the measured shower shape as a function of the absorber depth with a Monte-Carlo simulation is given.

Charged particle multiplicities in π−1,K− and\(\bar p\) interactions with nuclei at 40 GeV/c

AbstractInteractions of 40 GeV/c πp-,K− and

Measurement of shower development and its Molière radius with a four-plane LumiCal test set-up

\bar p

EXPECTED ELECTROMAGNETIC AND NEUTRON DOSES FOR THE BEAMCAL AT ILD

on Li, C, S, Cu, CsI and Pb were studied with the RISK-streamer chamber spectrometer. We present multiplicities of negatively charged particles, as well as of protons, and the correlations between them. The normalized mean multiplicity of negative particles,R−, depends on