We revisit the description of inverse Compton scattering sources and the photon beams generated therein, emphasizing the behavior of their phase space density distributions and how they depend upon ...those of the two colliding beams of electrons and photons. The main objective is to provide practical formulas for bandwidth, spectral density, brilliance, which are valid in general for any value of the recoil factor, i.e. both in the Thomson regime of negligible electron recoil, and in the deep Compton recoil dominated region, which is of interest for gamma-gamma colliders and Compton sources for the production of multi-GeV photon beams. We adopt a description based on the center of mass reference system of the electron-photon collision, in order to underline the role of the electron recoil and how it controls the relativistic Doppler/boost effect in various regimes. Using the center of mass reference frame greatly simplifies the treatment, allowing us to derive simple formulas expressed in terms of rms momenta of the two colliding beams (emittance, energy spread, etc.) and the collimation angle in the laboratory system. Comparisons with Monte Carlo simulations of inverse Compton scattering in various scenarios are presented, showing very good agreement with the analytical formulas: in particular we find that the bandwidth dependence on the electron beam emittance, of paramount importance in Thomson regime, as it limits the amount of focusing imparted to the electron beam, becomes much less sensitive in deep Compton regime, allowing a stronger focusing of the electron beam to enhance luminosity without loss of mono-chromaticity. A similar effect occurs concerning the bandwidth dependence on the frequency spread of the incident photons: in deep recoil regime the bandwidth comes out to be much less dependent on the frequency spread. The set of formulas here derived are very helpful in designing inverse Compton sources in diverse regimes, giving a quite accurate first estimate in typical operational conditions for number of photons, bandwidth, spectral density and brilliance values—the typical figures of merit of such radiation sources.
Abstract
Renewed international interest in muon colliders motivates
the continued investigation of the impacts of beam-induced
background on detector performance. This continues the effort
initiated ...by the Muon Accelerator Program and carried out until
2017. The beam-induced background from muon decays directly impacts
detector performance and must be mitigated by optimizing the overall
machine design, with particular attention paid to the machine
detector interface region. In order to produce beam-induced
background events and to study their characteristics in coordination
with the collider optimization, a flexible simulation approach is
needed. To achieve this goal we have chosen to utilize the
combination of LineBuilder and Monte Carlo FLUKA codes. We report
the results of beam-induced background studies with these tools
obtained for a 1.5 TeV center of mass energy collider
configuration. Good agreement with previous simulations using the
MARS15 code demonstrates that our choice of tools meet the accuracy
and performance requirements to perform future optimization studies
on muon collider designs.
A systematic study of the polarization of x-gamma rays produced in Thomson and Compton scattering is presented, in both classical and quantum schemes. Numerical results and analytical considerations ...let us to establish the polarization level as a function of acceptance, bandwidth and energy. Few sources have been considered: the SPARC_LAB Thomson device, as an example of a x-ray Thomson source, ELI-NP, operating in the gamma range. Then, the typical parameters of a beam produced by a plasma accelerator has been analyzed. In the first case, with bandwidths up to 10%, a contained reduction (<10% ) in the average polarization occurs. In the last case, for the nominal ELI-NP relative bandwidth of 5×10−3 , the polarization is always close to 1. For applications requiring larger bandwidth, however, a degradation of the polarization up to 30% must be taken into account. In addition, an all optical gamma source based on a plasma accelerated electron beam cannot guarantee narrow bandwidth and high polarization operational conditions required in nuclear photonics experiments.
Abstract
The measurement of physics processes at new energy frontier
experiments requires excellent spatial, time, and energy resolutions
to resolve the structure of collimated high-energy jets. In a ...future
Muon Collider, the beam-induced backgrounds (BIB) represent the main
challenge in the design of the detectors and of the event
reconstruction algorithms. The technology and the design of the
calorimeters should be chosen to reduce the effect of the BIB, while
keeping good physics performance. Several requirements can be
inferred: i) high granularity to reduce the overlap of BIB particles
in the same calorimeter cell; ii) excellent timing (of the order of
100 ps) to reduce the out-of-time component of the BIB; iii)
longitudinal segmentation to distinguish the signal showers from the
fake showers produced by the BIB; iv) good energy resolution (less
than 10%/
√E
) to obtain good physics performance, as has
been already demonstrated for conceptual particle flow calorimeters.
Our proposal consists of a semi-homogeneous electromagnetic
calorimeter based on lead fluoride crystals (PbF
2
) read out by
surface-mount UV-extended Silicon Photomultipliers (SiPMs): the
Crilin calorimeter. In this paper, the performance of the Crilin
calorimeter in the Muon Collider framework for hadron jets
reconstruction has been analyzed. We report the characterisation of
individual components together with the development of a small-scale
prototype, consisting of 2 layers of 3 × 3 crystals each.
To describe a new extended depth of focus intraocular lens (IOL) design offering multifocality by the variation of spherical aberration in the central optical zone.
The new IOL (Mini WELL; SIFI, ...Catania, Italy) is an aspheric IOL with positive spherical aberration in the central 2-mm zone and negative spherical aberration in the pericentral 1-mm annulus, the amount of which was determined by specific optic calculation. The new IOL design was tested at the optical bench to investigate depth of focus and sensitivity to tilt, decentration, and angle Kappa. Visual acuity simulations were obtained from distance (4 m) to near (0.5 m).
Modulation transfer function (MTF) for a 3-mm pupil was 0.35 to 0.40 for distance vision and 0.25 to 0.30 for intermediate and near vision. MTF for a 4.5-mm pupil was 0.40 to 0.55 and 0.10 to 0.20, respectively. These values were not influenced by tilt up to ±2.5°, by decentration up to ±0.5 mm, or by angle Kappa up to 9°. Visual acuity simulations indicated good visual acuity up to 2.00 D of pseudoaccommodation.
The new IOL with double spherical aberration in the central 3-mm zone offered good MTF over a wide dioptric interval, suggesting good visual acuity between 4 m and 50 cm. This extended depth of focus IOL with no diffractive rings is expected to produce lower unwanted optical phenomena than current multifocal IOLs. J Refract Surg. 2017;33(6):389-394..
This paper explores the transition between Compton Scattering and Inverse Compton Scattering (ICS), which is characterized by an equal exchange of energy and momentum between the colliding particles ...(electrons and photons). This regime has been called Symmetric Compton Scattering (SCS) and has the unique property of eliminating the energy-angle correlation of scattered photons, and, when the electron recoil is large, transferring monochromaticity from one colliding beam to the other, resulting in back-scattered photon beams that are intrinsically monochromatic. The paper suggests that large-recoil SCS or quasi-SCS can be used to design compact intrinsic monochromatic γ-ray sources based on compact linacs, thus avoiding the use of GeV-class electron beams together with powerful laser/optical systems as those typically required for ICS sources. Furthermore, at low recoil and low energy collisions (in the 10 keV energy range), SCS can be exploited to heat the colliding electron beam, which is widely scattered with large transverse momenta over the entire solid angle, offering a technique to trap electrons into magnetic bottles for plasma heating.
ELI–nuclear physics (NP) Gamma Beam System (GBS) is an intense and monochromatic gamma beam source based on inverse Compton interaction, currently being built in Bucharest, Romania. The gamma beam ...produced, with energy ranging from 0.2 to 20MeV, energy bandwidth 0.5% and flux of about 108photons/s, will be devoted to investigate a broad range of applications such as nuclear physics, astrophysics, material science and life sciences. The radiation produced by an inverse Compton interaction is not intrinsically monochromatic. In fact, the energy of the photons produced is related to the emission angle, therefore the energy bandwidth can be modified adjusting the collimation of the gamma beam. In order to define the optimal layout and evaluate the performance of a collimation system for the ELI–NP–GBS low-energy beamline (0.2–3.5MeV), a detailed Monte Carlo simulation activity has been carried out. The simulation, using Geant4 and MCNPX codes, included the transport of the gamma beam from the interaction point to the experimental area passing through vacuum pipes, vacuum chambers, collimation system and relative shielding. The effectiveness of the collimation system, in obtaining the required energy distribution and avoiding the contamination due to secondary radiation production, was evaluated. Also, the background radiation generated by collimation and the shielding layout have been studied.
Dual color x rays from Thomson or Compton sources Petrillo, V.; Bacci, A.; Curatolo, C. ...
Physical review special topics. Accelerators and beams,
02/2014, Letnik:
17, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We analyze the possibility of producing two-color x or γ radiation by Thomson/Compton backscattering between a high intensity laser pulse and a two-energy level electron beam, constituted by a couple ...of beamlets separated in time and/or energy obtained by a photoinjector with comb laser techniques and linac velocity bunching. The parameters of the Thomson source at SPARC_LAB have been simulated, proposing a set of realistic experiments.
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