LIBO is a proton accelerator that operates at
3
GHz
, the same frequency as the one adopted in the about 7500 electron linacs used for radiotherapy all over the world. Such a high frequency was ...chosen to obtain a large gradient (on average more than
10
MV/m
), and thus a short linac (about
15
m
) to boost the energy of the protons, extracted at about
60
MeV
from a cyclotron, up to the
200
MeV
needed for the treatment of deep-seated tumours.
This paper describes the design study of the full
3
GHz
Side Coupled Linac (modular structure, nine modules) and the construction and tests of the LIBO prototype (first module), which was built to accelerate protons from 62 to
74
MeV
with an RF peak power of
4.4
MW
. The items discussed are the beam dynamics parameters of the module (longitudinal and transverse acceptances), the constructional elements and procedures, the accuracies of the various mechanical elements, the cooling system, the RF tuning, the RF measurement and the RF power tests. These tests showed that, after a short conditioning time, the gradient in each of the four tanks of the module could reach
28.5
MV/m
, much larger than the nominal project value
(15.8
MV/m)
. The last section of the paper describes the successful acceleration tests performed at the Laboratori Nazionali del Sud of INFN in Catania with a solid-state
3
GHz
modulator lent by IBA.
Performance of the DELPHI detector Abreu, P.; Ajinenko, I.; Aleksan, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
1996, Letnik:
378, Številka:
1
Journal Article
Recenzirano
Odprti dostop
DELPHI (DEtector with Lepton, Photon and Hadron Identification) is a detector for e
+e
− physics, designed to provide high granularity over a 4π solid angle, allowing an effective particle ...identification. It has been operating at the LEP (Large Electron-Positron) collider at CERN since 1989. This article reviews its performance.
The DELPHI detector at LEP
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/1991
Journal Article
During 1993 and 1995 LEP was run at 3 energies near the Z\(^0\) peak in order to give improved measurements of the mass and width of the resonance. During 1994, LEP operated only at the Z\(^0\) peak. ...In total DELPHI accumulated data corresponding to an integrated luminosity of approximately 116 pb\(^{-1}\). Analyses of the hadronic cross-sections and of the cross-sections and forward-backward asymmetries in the leptonic channels used the most precise evaluations of the LEP energies. In the dimuon channel, events with a photon radiated from the initial state have been used to probe the cross-sections and asymmetries down to PETRA energies. Model independent fits to all DELPHI lineshape and asymmetry data from 1990 to 1995 have been carried out giving values of the resonance parameters:These values are significantly more precise than those previously published. The results are interpreted in terms of the Standard Model.
The processes involved in the pulsed laser crystallization of amorphous silicon thin films were studied using transient reflection measurements. A model of the melting and solidification induced by ...the laser exposure, based on a one-dimensional calculation of the heat flow, was used to simulate the time-dependent reflectivity, yielding agreement with the experiments. Two laser beams interfering on the sample surface lead to the growth of long grains (up to 1.5
μm), with a well-defined orientation. We conclude that this lateral growth results from explosive crystallization combined with liquid phase growth.
Using D
∗+
mesons exclusively reconstructed in the DELPHI detector at LEP, an excess of 66±14(stat.) events is observed in the D
∗+π
+π
−
final state with a mass of 2637±2(stat.)±6(syst.) MeV/
c
2 ...and a full width smaller than 15 MeV/
c
2 (95% C.L.). This signal is compatible with the expected decay of a radially excited D
∗′
(
J
P
=1
−) meson.
A XeCl excimer laser (
λ=308 nm) has been used to anneal Indium Tin Oxide (ITO) films deposited at 25 °C using DC magnetron sputtering. With increasing laser fluence, the film crystallinity was ...improved while retaining the as-deposited 〈111〉 texture. As a result of laser irradiation, the sheet resistance of 100 nm ITO films decreased from 191 Ω/□ (1.91×10
−3 Ω cm) to 25 Ω/□ (2.5×10
−4 Ω cm), while the optical transmittance in the visible range increased from 70% to more than 85%. Surface roughness and etching properties were also significantly improved following laser annealing.
Laser pulses in the nanosecond range were used to crystallize and structure (lateral dimensions≤1
μm) amorphous germanium thin films. The crystallized material consists of grains with sizes ...increasing from about 5 to more than 20 nm as a function of laser pulse energy. Arrays of polycrystalline Ge dots (diameter ∼1
μm, period ∼5
μm) were produced by bringing three laser beams to interference on the sample surface. These arrays can be used as seeds for solid-phase growth of polycrystalline areas by thermal annealing below 450°C.
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