289 research outputs found
Influence of incoherent scattering on stochastic deflection of high-energy negative particle beams in bent crystals
An investigation on stochastic deflection of high-energy negatively charged
particles in a bent crystal was carried out. On the basis of analytical
calculation and numerical simulation it was shown that it exists a maximum
angle at which most of the beam is deflected. The existence of a maximum, which
is taken in the correspondence of the optimal radius of curvature, is a novelty
with respect to the case of positively charged particles, for which the
deflection angle can be freely increased by increasing the crystal length. This
difference has to be ascribed to the stronger contribution of incoherent
scattering affecting the dynamics of negative particles that move closer to
atomic nuclei and electrons. We therefore identified the ideal parameters for
the exploitation of axial confinement for negatively charged particle beam
manipulation in future high-energy accelerators, e.g., ILC or muon colliders
Electromagnetic dipole moments of charged baryons with bent crystals at the LHC
We propose a unique program of measurements of electric and magnetic dipole
moments of charm, beauty and strange charged baryons at the LHC, based on the
phenomenon of spin precession of channeled particles in bent crystals. Studies
of crystal channeling and spin precession of positively- and negatively-charged
particles are presented, along with feasibility studies and expected
sensitivities for the proposed experiment using a layout based on the LHCb
detector.Comment: 19 pages, 13 figure
Progress towards the first measurement of charm baryon dipole moments
Electromagnetic dipole moments of short-lived particles are sensitive to physics within and beyond the Standard Model of particle physics but have not been accessible experimentally to date. To perform such measurements it has been proposed to exploit the spin precession of channeled particles in bent crystals at the LHC. Progress that enables the first measurement of charm baryon dipole moments is reported. In particular, the design and characterization on beam of silicon and germanium bent crystal prototypes, the optimization of the experimental setup, and advanced analysis techniques are discussed. Sensitivity studies show that first measurements of Λ+c and Ξ+c baryon dipole moments can be performed in two years of data taking with an experimental setup positioned upstream of the LHCb detector.
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A high-performance custom photodetection system to probe the light yield enhancement in oriented crystals
Scintillating homogeneous detectors represent the state of the art in
electromagnetic calorimetry. Moreover, the currently neglected crystalline
nature of the most common inorganic scintillators can be exploited to achieve
an outstanding performance boost in terms of compactness and energy resolution.
In fact, it was recently demonstrated by the AXIAL/ELIOT experiments that a
strong reduction in the radiation length inside PWO, and a subsequent
enhancement in the scintillation light emitted per unit thickness, are attained
when the incident particle trajectory is aligned with a crystal axis within
. A SiPM-based system has been developed to directly probe this
remarkable effect by measuring the scintillation light emitted by a PWO sample.
The same concept could be applied to full-scale detectors that would feature a
design significantly more compact than currently achievable and unparalleled
resolution in the range of interest for present and future experiments
The UA9 experimental layout
The UA9 experimental equipment was installed in the CERN-SPS in March '09
with the aim of investigating crystal assisted collimation in coasting mode.
Its basic layout comprises silicon bent crystals acting as primary
collimators mounted inside two vacuum vessels. A movable 60 cm long block of
tungsten located downstream at about 90 degrees phase advance intercepts the
deflected beam.
Scintillators, Gas Electron Multiplier chambers and other beam loss monitors
measure nuclear loss rates induced by the interaction of the beam halo in the
crystal. Roman pots are installed in the path of the deflected particles and
are equipped with a Medipix detector to reconstruct the transverse distribution
of the impinging beam. Finally UA9 takes advantage of an LHC-collimator
prototype installed close to the Roman pot to help in setting the beam
conditions and to analyze the efficiency to deflect the beam. This paper
describes in details the hardware installed to study the crystal collimation
during 2010.Comment: 15pages, 11 figure, submitted to JINS
Development of an advanced modular setup for the on beam characterization of oriented crystals
Recently, the particle physics community has put an increasing effort in developing radiation detectors and equipment based on oriented crystals. A key feature that distinguishes an oriented crystal from the ordinary matter is the reduction of the radiation length (X0) seen by electrons, positrons and photons crossing the lattice along one of its symmetry axes. This effect has been experimentally observed only in the last few decades and with samples limited in number, composition and length. In order to characterize a variety of oriented crystals with a standardized procedure, the STORM Collaboration has developed an advanced modular setup, which allows to study the features of any crystal sample with both electron (or positron) and photon beams. This contribution describes the key elements of this setup, namely silicon strip tracking detectors, plastic scintillators, Silicon Photo-Multipliers (SiPMs) coupled to the crystal under test, a photon calorimeter and an electromagnetic spectrometer
Development of an advanced modular setup for the on beam characterization of oriented crystals
Recently, the particle physics community has put an increasing effort in developing radiation detectors and equipment based on oriented crystals. A key feature that distinguishes an oriented crystal from the ordinary matter is the reduc-tion of the radiation length (X0) seen by electrons, positrons and photons crossing the lattice along one of its symmetry axes. This effect has been experimentally ob-served only in the last few decades and with samples limited in number, composition and length. In order to characterize a variety of oriented crystals with a standardized procedure, the STORM Collaboration has developed an advanced modular setup, which allows to study the features of any crystal sample with both electron (or positron) and photon beams. This contribution describes the key elements of this setup, namely silicon strip tracking detectors, plastic scintillators, Silicon Photo -Multipliers (SiPMs) coupled to the crystal under test, a photon calorimeter and an electromagnetic spectrometer
High-efficiency deflection of high energy protons due to channeling along the (110) axis of a bent silicon crystal
A deflection efficiency of about 61% was observed for 400 GeV/c protons due to channeling, most strongly along the 〈110〉 axis of a bent silicon crystal. It is comparable with the deflection efficiency in planar channeling and considerably larger than in the case of the 〈111〉 axis. The measured probability of inelastic nuclear interactions of protons in channeling along the 〈110〉 axis is only about 10% of its amorphous level whereas in channeling along the (110) planes it is about 25%. High efficiency deflection and small beam losses make this axial orientation of a silicon crystal a useful tool for the beam steering of high energy charged particles
Observation of focusing of 400 GeV/c proton beam with the help of bent crystals
The results of observation and studies of focusing of 400 GeV/ c proton beam with the help of bent single crystals are presented. Two silicon crystals have been used in the measurements. The focal length of the first and second crystals is found to be 1.48 m and 0.68 m, respectively. The mean square size of the horizontal profile in the focus was 3.1 and 4.3 times as small as at the exit of the crystals
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