Speaker
Mrs
Sonia Luengo
(La Salle, School of Engineering, Universitat Ramon Llull)
Description
The SPD (Scintillator Pad Detector) is a part of LHCb calorimetry. Its function is
to discriminate between charged particles and neutrals for the LHCb level0 trigger.
This detector uses scintillator pad readout by wavelength shifting (WLS) fibbers
that are coupled to MAPMT via clear plastic fibbers. The specific features of the
SPD detector are the high granularity in the inner part of the detector, and the
use of 64-channel photomultiplier tubes with small pixel dimension. The choice of a
MAPMT allowed to design a fast, multi-channel pad detector with a reduced cost per
channel..
The signal outing the SPD PMTs has large fluctuations in the signal pulse shape
since the average of photoelectrons is only about 20-30 due to the response of the
WLS fibre, which has low decay time. This fact causes another bothering trouble:
the potential tail of a high amplitude event could cross the threshold and provoke
a fake trigger. Thus, pile-up correction is needed.
SPD Readout system is performed by an specific ASIC which integrates the signal,
makes the pile-up compensation, and compares the level obtained to a programmable
threshold (distinguish electrons and photons), an FPGA which programmes the ASIC
threshold and pile-up subtraction and finally LVDS serializers, in order to send
information to the first level trigger system.
Author
Mrs
Sonia Luengo
(La Salle, School of Engineering, Universitat Ramon Llull)
Co-authors
Mr
Albert Comerma
(Universitat de Barcelona)
Mr
David Gascon
(Universitat de Barcelona)
Mr
Lluis Garrido
(Universitat de Barcelona)
Mr
Xavier Vilasis-Cardona
(La Salle, school of Engineering, Universitat Ramon Llull)
