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18–22 Sept 2017
Congress Centre "Le Majestic"
Europe/Zurich timezone

Design and status of the Mu2e crystal calorimeter

18 Sept 2017, 15:30
15m
Congress Centre "Le Majestic"

Congress Centre "Le Majestic"

Chamonix (FR)
Oral presentation S03_Application 1 (Orals) Applications

Speaker

Dr Stefano Miscetti (LNF -INFN)

Description

The Mu2e experiment at Fermilab searches for the charged-lepton flavour violating
neutrino-less conversion of a negative muon into an electron in the field of
a aluminum nucleus. The dynamics of such a process is well
modelled by a two-body decay, resulting in a mono-energetic electron with
an energy slightly below the muon rest mass (104.967 MeV).
If no events are observed in three years of running, Mu2e will set a limit on
the ratio between the conversion rate and the capture rate \convrate of 6 × 1017 (@ 90% C.L.). This will improve the current
limit by four orders of magnitude~\cite{MU2ETDR}.

A very intense pulsed muon beam (1010μ/ sec) is stopped on
a target inside a very long solenoid where the detector is located.
The Mu2e detector is composed of a tracker and an electromagnetic
calorimeter and an external veto for cosmic rays surrounding the
solenoid. The calorimeter plays an important
role in providing excellent particle identification capabilities, a fast online trigger filter
while aiding the track reconstruction capabilities. It should be able to keep
functionality in an environment where the n, p and photon
background from muon capture processes and beam flash
events deliver a dose of ~ 120 Gy/year in the hottest area.
It will also need to work in 1 T axial magnetic
field and a 104 torr vacuum. The calorimeter requirements are
to provide a large acceptance for 100 MeV electrons and reach:
(a) a time resolution better than 0.5 ns @ 100 MeV;
(b) an energy resolution {\it O(10%)} @ 100 MeV and
(c) a position resolution of 1 cm.

The calorimeter consists of two disks, each one made of 674 pure CsI
crystals read out by two large area array 2×3 of UV-extended
SiPM 6×6 mm2. We report here all progresses done for the construction and test of the
Module-0 prototype that is an array of 51 pre-production crystals from
St.Gobain, Siccas and Amcrys firms. Each crystal has been
readout by two pre-production Mu2e SiPMs selected among the
ones produced by Hamamatsu, Sensl or Advansid . Each photosensor
has been amplified and regulated in bias voltage by means of
a FEE custom chip. Final digitization stage is also custom and relies
on a 5 ns sampling. The module-0 will be exposed to an electron
beam in the energy range around 100 MeV at the BTF (Beam Test
Facility) in Frascati. Preliminary results of timing and energy
resolution at normal incidence will be shown as well as dependence
of response and resolution as a function of the impinging angle.

Author

Dr Stefano Miscetti (LNF -INFN)

Presentation materials