4,296 research outputs found
The ultimate resolution drift chamber
It will be shown that, by collecting on the sense wire all primary ionization and recording the drift times and amplitudes of all individual ionization electrons, spatial resolution and particle identification can be pushed to their theoretical limits of accuracy. Such a method will prove to be ideal for colliders like SuperB , where accuracies of the order of a few percent in dE / dx are required for particle identification, or like the Linear Collider , where the momentum resolution is needed at the level of a few tenths of a percent for 100 GeV / c momenta particles
New concepts for light mechanical structures of cylindrical drift chambers
A significant reduction in the amount of material at the end plates of a drift chamber can be obtained by the simple consideration of separating, in the mechanical structure, the gas containment function from the wire tension support function. According to this scheme, the wires are anchored to a self-sustaining light structure ("wire cage") surrounded by a very thin skin ("gas envelope") of suitable profile to compensate for the gas differential pressure with respect to the outside.
The "wire cage" is schematically made of a set of radial spokes, constrained into a polygonal shape at the inner ends and extended to the outer endplate rim, thus subdividing the chamber in identical sectors. The drift chamber is, then, built by stacking up radially, in each of the sectors and between adjacent spokes, printed circuit boards, where the ends of the wires are soldered, alternated with proper spacers, to define the cell width.
A system of adjustable tie-rods steers the wire tension to the outer endplate rim, where a rigid cylindrical carbon fibre support structure, bearing the total wire load, is attached.
Two thin carbon fibre domes, free to deform under the gas pressure without affecting the wire tension and conveniently shaped to minimize the stress at the inner rim, contribute to the "gas envelope" and, together with an inner thin cylindrical foil and with the outer structural support, enclose the gas volume
Commissioning of the MEG II tracker system
The MEG experiment at the Paul Scherrer Institut (PSI) represents the state
of the art in the search for the charged Lepton Flavour Violating (cLFV) decay. With the phase 1, MEG set the new world best
upper limit on the \mbox{BR}(\mu^+ \rightarrow e^+ \gamma) < 4.2 \times
10^{-13} (90% C.L.). With the phase 2, MEG II, the experiment aims at reaching
a sensitivity enhancement of about one order of magnitude compared to the
previous MEG result. The new Cylindrical Drift CHamber (CDCH) is a key detector
for MEG II. CDCH is a low-mass single volume detector with high granularity: 9
layers of 192 drift cells, few mm wide, defined by wires in a
stereo configuration for longitudinal hit localization. The filling gas mixture
is Helium:Isobutane (90:10). The total radiation length is
\mbox{X}_0, thus minimizing the Multiple Coulomb Scattering (MCS)
contribution and allowing for a single-hit resolution m and an
angular and momentum resolutions of 6 mrad and 90 keV/c respectively. This
article presents the CDCH commissioning activities at PSI after the wiring
phase at INFN Lecce and the assembly phase at INFN Pisa. The endcaps
preparation, HV tests and conditioning of the chamber are described, aiming at
reaching the final stable working point. The integration into the MEG II
experimental apparatus is described, in view of the first data taking with
cosmic rays and beam during the 2018 and 2019 engineering runs. The
first gas gain results are also shown. A full engineering run with all the
upgraded detectors and the complete DAQ electronics is expected to start in
2020, followed by three years of physics data taking.Comment: 10 pages, 12 figures, 1 table, proceeding at INSTR'20 conference,
accepted for publication in JINS
Single-hit resolution measurement with MEG II drift chamber prototypes
Drift chambers operated with helium-based gas mixtures represent a common
solution for tracking charged particles keeping the material budget in the
sensitive volume to a minimum. The drawback of this solution is the worsening
of the spatial resolution due to primary ionisation fluctuations, which is a
limiting factor for high granularity drift chambers like the MEG II tracker. We
report on the measurements performed on three different prototypes of the MEG
II drift chamber aimed at determining the achievable single-hit resolution. The
prototypes were operated with helium/isobutane gas mixtures and exposed to
cosmic rays, electron beams and radioactive sources. Direct measurements of the
single hit resolution performed with an external tracker returned a value of
110 m, consistent with the values obtained with indirect measurements
performed with the other prototypes.Comment: 18 pages, 18 figure
ATLAS RPC Quality Assurance results at INFN Lecce
The main results of the quality assurance tests performed on the Resistive
Plate Chamber used by the ATLAS experiment at LHC as muon trigger chambers are
reported and discussed.
Since July 2004, about 270 RPC units has been certified at INFN Lecce site
and delivered to CERN, for being integrated in the final muon station of the
ATLAS barrel region.
We show the key RPC characteristics which qualify the performance of this
detector technology as muon trigger chamber in the harsh LHC enviroments.
These are dark current, chamber efficiency, noise rate, gas volume
tomography, and gas leakage.Comment: Comments: 6 pages, 1 table, 9 figures Proceedings of XXV Physics in
Collision-Prague, Czech Republic, 6-9 July 200
Design, status and perspective of the Mu2e crystal calorimeter
The Mu2e experiment at Fermilab will search for the charged lepton flavor
violating process of neutrino-less coherent conversion in the field
of an aluminum nucleus. Mu2e will reach a single event sensitivity of about
that corresponds to four orders of magnitude improvements
with respect to the current best limit. The detector system consists of a straw
tube tracker and a crystal calorimeter made of undoped CsI coupled with Silicon
Photomultipliers. The calorimeter was designed to be operable in a harsh
environment where about 10 krad/year will be delivered in the hottest region
and work in presence of 1 T magnetic field. The calorimeter role is to perform
/e separation to suppress cosmic muons mimiking the signal, while
providing a high level trigger and a seeding the track search in the tracker.
In this paper we present the calorimeter design and the latest RD results.Comment: 4 pages, conference proceeding for a presentation held at TIPP'2017.
To be published on Springer Proceedings in Physic
The front end electronics for the drift chamber readout in MEG experiment upgrade
Front-end electronics plays an essential role in drift chambers for time resolution and, therefore, spatial resolution. The use of cluster timing techniques, by measuring the arriving times of all the individual ionization clusters after the first one, may enable to reach resolutions even below 100 μm in the measurement of the impact parameter. A high performance front-end electronics, characterized by low distortion, low noise and a wide bandwidth has been developed with the purpose to implement cluster timing techniques in the new drift chamber for the upgrade of the MEG experiment at Paul Sherrer Institut (CH)
Quality Assurance on a custom SiPMs array for the Mu2e experiment
The Mu2e experiment at Fermilab will search for the coherent
conversion on aluminum atoms. The detector system consists of a straw tube
tracker and a crystal calorimeter. A pre-production of 150 Silicon
Photomultiplier arrays for the Mu2e calorimeter has been procured. A detailed
quality assur- ance has been carried out on each SiPM for the determination of
its own operation voltage, gain, dark current and PDE. The measurement of the
mean-time-to-failure for a small random sample of the pro-production group has
been also completed as well as the determination of the dark current increase
as a function of the ioninizing and non-ioninizing dose.Comment: 4 pages, 10 figures, conference proceeding for NSS-MIC 201
The Mu2e undoped CsI crystal calorimeter
The Mu2e experiment at Fermilab will search for Charged Lepton Flavor
Violating conversion of a muon to an electron in an atomic field. The Mu2e
detector is composed of a tracker, an electromagnetic calorimeter and an
external system, surrounding the solenoid, to veto cosmic rays. The calorimeter
plays an important role to provide: a) excellent particle identification
capabilities; b) a fast trigger filter; c) an easier tracker track
reconstruction. Two disks, located downstream of the tracker, contain 674 pure
CsI crystals each. Each crystal is read out by two arrays of UV-extended SiPMs.
The choice of the crystals and SiPMs has been finalized after a thorough test
campaign. A first small scale prototype consisting of 51 crystals and 102 SiPM
arrays has been exposed to an electron beam at the BTF (Beam Test Facility) in
Frascati. Although the readout electronics were not the final, results show
that the current design is able to meet the timing and energy resolution
required by the Mu2e experiment.Comment: 6 pages, 8 figures, proceedings of the "Calorimetry for the high
energy frontier (CHEF17)" conference, 2-6 October 2017, Lyon, Franc
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