[ Home | Contents | Search | Start a new article | Reply | Next | Previous | Up ]
From: Jorgen.Christiansen@cern.ch
Date: 7/3/00
Time: 8:02:24 AM
Remote Name: 137.138.142.33
Remote User:
Dear LHCb electronics compatriots It has during some discussions about calibration and time alignment of sub-detectors in LHCb come up that it would be very interesting to have LHC run with isolated bunch collisions during limited time periods. Isolated bunch collisions will in many cases make the calibration and time alignment much easier as the background rates will be significantly reduced and pileup (or spill-over as some call it) from previous bunch collisions will disappear. In some cases such a single bunch mode, during a short time period in the beginning of each year, will enable the front-end electronics architecture to be significantly simplified ( and cheaper !). It is not yet defined how many real bunches there would be in the LHC bunch structure in such a mode. To understand if LHCb in general can benefit from such a LHC mode, I would appreciate if anybody who thinks that their sub-detector can benefit from this, sends me an Email with a short description of the potential gain. It is also important to understand if a few days in this running mode is sufficient before each running season (year). If we see a significant advantage of such a mode, then we will investigate this possibility in more detail with the LHC machine and finally maybe make an official request to LHC. We also need to understand if the other LHC experiments would support such a request. An other point which has come up during discussions about calibration and time alignment is the question of triggering. In principle we can not assume that the trigger system can generate real triggers before the sub-detectors and the trigger systems have been correctly time aligned. It is though of interest to have some kind of a simple trigger just to indicate if a real interaction has occurred ( ~ one in four bunch collisions ). Such a simple trigger could be made rather straight forward with a small fast and simple scintillating detector. It would potentially also be possible to select high multiplicity interactions to improve statistics for the time alignment and calibration. Please let me know if you think you would have significant advantages from such a simple trigger. We will discuss these points in more detail in Milan and I would be pleased if anybody wants to make a presentation of their view point on these matters. Best regards Jorgen