Threshold calibration and threshold finding procedure in various LHCb muon MWPC

Threshold calibration and threshold finding procedure in the LHCb muon MWPCs are discussed in this note. Two thresholds in units of charge [fC] are needed in principle: one for the anodes, e.g. 12fC, and one for the cathodes, e.g. 6fC. In reality 120,000 individual thresholds due to variations in offset in CARIOCA chip, different detector capacitances of pads with different size resulting variations in sensitivity from chamber to chamber have to be calculated in register units [r.u.] and move to the threshold registers located in DIALOG chip. The general formula for thresholds in [r.u.] for a given charge unit [fC] is presented. A list of detector capacitance and the averaged sensitivity needed for threshold calculations are given for the inner-most LHCb muon MWPCs in Appendix

On LHCb muon MWPC grounding

My goal is to study how a big MWPC system, in particular the LHCb muon system, can be protected against unstable operation and multiple spurious hits, produced by incorrect or imperfect grounding in the severe EM environment of the LHCb experiment. A mechanism of penetration of parasitic current from the ground loop to the input of the front-end amplifier is discussed. A new model of the detector cell as the electrical bridge is considered. As shown, unbalance of the bridge makes detector to be sensitive to the noise in ground loop. Resonances in ground loop are specified. Tests of multiple-point and single-point grounding conceptions made on mock-up are presented

Procedure for determination and setting of thresholds implemented in the LHCb Muon system

The LHCb Muon system consists of 1368 Multi Wire Proportional Chambers of different size and readout for a total of ~120k electronics channels. The choice of the correct threshold to be applied to each channel can be made on the basis of the detector simulation or, as we suggest in this note, by measuring the noise parameters for each channel and consequently setting the desired values. When dealing with individual channels of the Muon system, the variations of the specific properties of each CARIOCA channel should be properly taken into account in order to fine tune the thresholds. The discriminator stage of the CARIOCA is characterized by a voltage bias that needs to be properly measured and taken into account in the threshold calculations. The procedure used for such calculations for the physical channels of the Muon system is discussed in detail in this note

From noise to signal - a new approach to LHCb muon optimization

One has to exploit the LHCb muon detector at the lowest possible gas gain and operational voltage in order to minimize the charge accumulated during 10 years of the LHCb experiment keeping the aging effects as low as possible. The detector lifetime prolongation 1.5-2 times can be achieved following the optimization of the LHCb muon system proposed in this note. An optimization of the LHCb muon system assumes: minimization of the electronics thresholds and detector gas gain, a choice of the working point near the knee of the efficiency plateau at high enough efficiency at stabilization the signal-to-noise ratio during long-term data taking runs by gas gain stabilization. An efficiency of each chamber tuned once by a time alignment remains constant at the constant gas gain. Cluster size, cross-talks, multi-hits become constant and minimal at constant and minimal gas gain. It is shown in the note how to reconstruct the noise distribution in each chamber already installed in the pit and to measure precisely offset and the Equivalent Noise Charge ($ENC$) both of which specify the minimal electronics threshold. $ENC$ enlargement problem related to threshold increasing at high particle rates is discussed. $ENC$ monitoring for each physical channel of the system during the LHCb experiment is proposed in order to detect aging of the LHCb muon system at the earliest stage and make correction

Measurement of the absolute gas gain and gain variations study in straw-tube detectors

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A new method based on noise counting to monitor the frontend electronics of the LHCb muon detector

A new method has been developed to check the correct behaviour of the frontend electronics of the LHCb muon detector. This method is based on the measurement of the electronic noise rate at different thresholds of the frontend discriminator. The method was used to choose the optimal discriminator thresholds. A procedure based on this method was implemented in the detector control system and allowed the detection of a small percentage of frontend channels which had deteriorated. A Monte Carlo simulation has been performed to check the validity of the method

Performance of the LHCb muon system with cosmic rays

The LHCb Muon system performance is presented using cosmic ray events collected in 2009. These events allowed to test and optimize the detector configuration before the LHC start. The space and time alignment and the measurement of chamber efficiency, time resolution and cluster size are described in detail. The results are in agreement with the expected detector performance.Comment: Submitted to JINST and accepte

Measurement of the front-end dead-time of the LHCb muon detector and evaluation of its contribution to the muon detection inefficiency

A method is described which allows to deduce the dead-time of the front-end electronics of the LHCb muon detector from a series of measurements performed at different luminosities at a bunch-crossing rate of 20 MHz. The measured values of the dead-time range from 70 ns to 100 ns. These results allow to estimate the performance of the muon detector at the future bunch-crossing rate of 40 MHz and at higher luminosity

A straw tube detector for the PANDA experiment

The PANDA experiment will be built at the FAIR facility in Darmstadt (Germany) to perform accurate tests of the strong interaction through pp and pA annihilations. This paper will address the design issue of the Straw Tube Tracker (STT), one of the two options proposed for the PANDA Central Tracker