Date: Thu, 08 Jan 1998 13:00:44 +0100 From: Klaus Ehret Cc: Andreas Schwarz , Ulrich Uwer , Joachim Spengler , Dietrich Wegener , Jochen Klenner , Klaus Ehret , Michael Funcke , Michael Symalla , Selim Issever , Stefan Spratte , Sven Schaller , Torsten Jagla , Valery Pugatch , "Hofmann, Werner" , Cristobal Padilla Subject: Ratemeasurement in 1998, Mounting of counters Newsgroups: desy.hera-b.general,desy.hera-b.tech-board,desy.hera-b.west-hall The requirement to the accuracy of rate measurement in 1998 is not yet finnaly definned, nevertheless we have to plan the hardware installation for the spring and need a running system in early june. Problem: To get precise rate information out of any HERA-B subdetector requires the existance of detectors with electronics AND the operation and at least a rough calibration. Even for the actual most promissing system the ECAL exists some uncertainty concerning availability and proper functionality in the beginning of the 1998 run. In the previous years the rate determination relied on the large acceptance scintillator counters (cake like structure - called triggerring) - mounted between VDS-vessel and magnet. This place is no longer available, because the OTR plans to install there a chamber. Baseline: It's worth to have a reasonable accurate rate measurement (O(10%)) already in the beginning of the 1998 run. Proposal: Install temporary the triggerring on the main plattform between magnet and RICH. This large acceptance counter is mainly necessary to calibrate other detectors (the large acceptance minimizes MC uncertainties) - and switch as soon as possible to these other counters. The main idea is to have enough data collected during the HERA electron vacuum conditioning phase and to remove the counters before (or in the beginning of) the Lumi run - which is expected for ~ mid august. Final Rate Measurement Devices: - ECAL: the colorimeter with its pretrigger inhibit card should provide the ultimative rate monitoring. Work is underway and in a good promising state. BUT: - requires lot of electronics, calibration and study -> works hopefully from august on - requires continous operation of ECAL or at least inner part !? - Charge integrators and Si-PIN-diodes Telescope near target: will provide information about individual wire contribution - system has to be calibrated in 1998 (>= 4 weeks - O(10 shifts)) -> low statistic counters O(10^-4 ... 10^-6) - SiPad detetctors near VDS exit window provides global rate monitoring (small acceptance O(%)) system has to be tested and calibrated in 1998 - we try to find a proper place for a set of small acceptance scintillating counters (hodoscopes) - in front of the outer part of the ECAL - anything else: ??? * there exists several plans from various groups to install rate monitors, but its quite unclear whether they will be realized * some HERA devices could be used for rough rate determination (factor of 2) Please send me your comment. We have to fix latest at the next collaboration meeting the plans !!! Are there any objections to mount the triggerring for some time in summer 1998 on the main plattform ? In case of serious remarks I propose to discuss and decide this point on the technical board meeting during the collaboration week in february. Best Regards Klaus /^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\ / Klaus Ehret (Uni-Dortmund EV) \ / DESY HERA-B Bldg. 66/8 Tel.: +49 40 8998 2845 \ / Notkestr.85 Fax.: +49 40 8998 4033 \ / D-22607 Hamburg Target-Handy: 0171-5589326 \ / \ / email: Klaus.Ehret@desy.de or ehret@desy.de \ /__________________________________________________________\