6,036 research outputs found
Crystals for high-energy calorimeters in extreme environments
Scintillating crystals are used for calorimetry in several high-energy
physics experiments. For many of them, performance has to be ensured in very
difficult operating conditions, like a high radiation environment and large
particle fluxes, which place constraints on response and readout time. An
overview is presented of the knowledge reached up to date, and of the newest
achievements in the field, with particular attention given to the performance
of Lead Tungstate crystals exposed to large particle fluxes.Comment: To be published in Proc. 9th ICATPP Conference on Astroparticle,
Particle, Space Physics, Detectors and Medical Physics Applications, Como,
Italy, October 17th to 21st, 200
High-energy proton induced damage study of scintillation light output from PbWO4 calorimeter crystals
Eight PbWO4 crystals produced for the electromagnetic calorimeter of the CMS
experiment at LHC have been irradiated in a 20 GeV/c proton beam up to fluences
of 5.4 E13 p/cm2. The damage recovery in these crystals, stored in the dark at
room temperature, has been followed for over a year. Comparative irradiations
with 60Co photons have been performed on seven other crystals using a dose rate
of 1 kGy/h. The issue whether hadrons cause a specific damage to the
scintillation mechanism has been studied through light output measurements on
the irradiated crystals using cosmic rays. The correlation between light output
changes and light transmission changes is measured to be the same for
proton-irradiated crystals and for gamma-irradiated crystals. Thus, within the
precision of the measurements and for the explored range of proton fluences, no
additional, hadron-specific damage to the scintillation mechanism is observed.Comment: 7 pages, 4 figure
First results on radiation damage in PbWO4 crystals exposed to a 20 GeV/c proton beam
We have exposed seven full length production quality crystals of the
electromagnetic calorimeter (ECAL) of the CMS detector to a 20 GeV/c proton
beam at the CERN PS accelerator. The exposure was done at fluxes of 10**12
p/cm**2/h and 10**13 p/cm**2/h and integral fluences of 10**12 p/cm**2 and
10**13 p/cm**2 were reached at both rates. The light transmission of the
crystals was measured after irradiation and suitable cooling time for induced
radioactivity to decrease to a safe level. First results of these measurements
are shown. The possible damage mechanisms are discussed and simulations based
on one possible model are presented. The implications for long-term operation
of CMS are discussed and it is shown that in the whole barrel and at least most
of the ECAL endcap hadron damage alone - even if cumulative - should not cause
the crystals to fail the CMS specification of an induced absorption coefficient
muIND < 1.5 /m during the first 10 years of LHC operation.Comment: 5 pages, to be published in Proc. ICATPP Conference on Astroparticle,
Particle, Space Physics, Detectors and Medical Physics Applications (Como,
Italy, 6 to 10 October 2003
Comparison between high-energy proton and charged pion induced damage in Lead Tungstate calorimeter crystals
A Lead Tungstate crystal produced for the electromagnetic calorimeter of the
CMS experiment at the LHC was cut into three equal-length sections. The central
one was irradiated with 290 MeV/c positive pions up to a fluence of (5.67 +-
0.46)x10^13 /cm^2, while the other two were exposed to a 24 GeV/c proton
fluence of (1.17 +- 0.11) x 10^13/ cm^2. The damage recovery in these crystals,
stored in the dark at room temperature, has been followed over two years. The
comparison of the radiation-induced changes in light transmission for these
crystals shows that damage is proportional to the star densities produced by
the irradiation.Comment: 7 pages, 4 figure
Performance studies of scintillating ceramic samples exposed to ionizing radiation
Scintillating ceramics are a promising, new development for various
applications in science and industry. Their application in calorimetry for
particle physics experiments is expected to involve an exposure to high levels
of ionizing radiation. In this paper, changes in performance have been measured
for scintillating ceramic samples of different composition after exposure to
penetrating ionizing radiation up to a dose of 38 kGy.Comment: 6 pages, 8 figures, to be published in the 2012 IEEE Nuclear Science
Symposium Conference Recor
Studies of the effect of charged hadrons on lead tungstate crystals
Scintillating crystals are used for calorimetry in several high-energy
physics experiments. For some of them, performance has to be ensured in
difficult operating conditions, like a high radiation environment, very large
particle fluxes and high collision rates. Results are presented here from a
thorough series of measurements concerning mainly the effect of charged hadrons
on lead tungstate. It is also shown how these results can be used to predict
the effect on crystals due to a given flux of particles.Comment: Submitted to Proceedings Calor 2008 - XIII International Conference
on Calorimetry in High Energy Physics, Pavia (Italy) 26-30 May 2008. To be
published in Journal of Physics: Conference Series (8 pages, 16 figures
A FLUKA study towards predicting hadron-specific damage due to high-energy hadrons in inorganic crystals for calorimetry
Hadrons emerging from high-energy collisions, as it is the case for protons
and pions at the CERN Large Hadron Collider, can produce a damage to inorganic
crystals that is specific and cumulative. The mechanism is well understood as
due to bulk damage from fragments caused by fission. In this paper, the
existing experimental evidence for lead tungstate, LYSO and cerium fluoride is
summarised, a study using FLUKA simulations is described and its results are
discussed and compared to measurements. The outcome corroborates the confidence
in the predictive power of such simulations applied to inorganic scintillators,
which are relevant to their adoption as scintillators for calorimetry.Comment: 15 pages, 8 figure
Crystals for high-energy calorimetry in extreme environments
Crystals are used as a homogeneous calorimetric medium in many high-energy
physics experiments. For some experiments, performance has to be ensured in
very difficult operating conditions, like a high radiation environment, very
large particle fluxes, high collision rates, placing constraints on response
and readout time. An overview is presented of recent achievements in the field,
with particular attention given to the performance of Lead Tungstate (PWO)
crystals exposed to high particle fluxes.Comment: To be published in Proc. of the Meeting of the Division of Particles
and Fields of the American Physical Society, DPF2004 (Riverside, USA, August
26th to 31st, 2004
A visualization of the damage in Lead Tungstate calorimeter crystals after exposure to high-energy hadrons
The anticipated performance of calorimeter crystals in the environment
expected after the planned High-Luminosity upgrade of the Large Hadron Collider
(HL-LHC) at CERN has to be well understood, before informed decisions can be
made on the need for detector upgrades. Throughout the years of running at the
HL-LHC, the detectors will be exposed to considerable fluences of fast hadrons,
that have been shown to cause cumulative transparency losses in Lead Tungstate
scintillating crystals. In this study, we present direct evidence of the main
underlying damage mechanism. Results are shown from a test that yields a direct
insight into the nature of the hadron-specific damage in Lead Tungstate
calorimeter crystals exposed to 24 GeV/c protons.Comment: 8 pages, 6 figure
Proof-of-principle of a new geometry for sampling calorimetry using inorganic scintillator plates
A novel geometry for a sampling calorimeter employing inorganic scintillators
as an active medium is presented. To overcome the mechanical challenges of
construction, an innovative light collection geometry has been pioneered, that
minimises the complexity of construction. First test results are presented,
demonstrating a successful signal extraction. The geometry consists of a
sampling calorimeter with passive absorber layers interleaved with layers of an
active medium made of inorganic scintillating crystals. Wavelength-shifting
(WLS) fibres run along the four long, chamfered edges of the stack,
transporting the light to photodetectors at the rear. To maximise the amount of
scintillation light reaching the WLS fibres, the scintillator chamfers are
depolished. It is shown herein that this concept is working for cerium fluoride
(CeF) as a scintillator. Coupled to it, several different types of
materials have been tested as WLS medium. In particular, materials that might
be sufficiently resistant to the High-Luminosity Large Hadron Collider
radiation environment, such as cerium-doped Lutetium-Yttrium Orthosilicate
(LYSO) and cerium-doped quartz, are compared to conventional plastic WLS
fibres. Finally, an outlook is presented on the possible optimisation of the
different components, and the construction and commissioning of a full
calorimeter cell prototype is presented.Comment: Submitted to Proceedings CALOR 2014, the 16th International
Conference on Calorimetry in High-Energy Physics, Giessen (Germany) 6 - 11
April 2014. To be published in Journal of Physics: Conference Series (10
pages, 15 figures
- …