We present an analytical model for electron self-injection in a nonlinear, multidimensional plasma wave excited by a short laser pulse in the bubble regime or by a short electron beam in the blowout ...regime. In these regimes, which are typical for electron acceleration, the laser radiation pressure or the electron beam charge pushes out background plasma electrons forming a plasma cavity--bubble--with a huge ion charge. The plasma electrons can be trapped in the bubble and accelerated by the plasma wakefields up to very high energies. The model predicts the condition for electron trapping and the trapping cross section in terms of the bubble radius and the bubble velocity. The obtained results are in a good agreement with results of 3D particle-in-cell simulations.
The response of silicon–silicon–CsI(Tl) and silicon–CsI(Tl) telescopes to fragments produced in nuclear interactions has been studied. The telescopes were developed within the FAZIA collaboration. ...The capabilities of two methods are compared: (a) the standard
Δ
E
–
E
technique and (b) the digital Pulse Shape Analysis technique (for identification of nuclear fragments stopped in a single Si-layer). In a test setup, nuclear fragments covering a large range in nuclear charge, mass and energy were detected. They were produced in nuclear reactions induced by a 35A MeV beam of
129Xe impinging on various targets. It was found that the
Δ
E
–
E
correlations allow the identification of all isotopes up to
Z
∼
25
. With the digital Pulse Shape Analysis it is possible to fully distinguish the charge of stopped nuclei up to the maximum available
Z (slightly over that of the beam,
Z=54).
The FAZIA project in Europe: R&D phase Bougault, R.; Poggi, G.; Barlini, S. ...
The European physical journal. A, Hadrons and nuclei,
2014/2, Letnik:
50, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The goal of the FAZIA Collaboration is the design of a new-generation 4
π
detector array for heavy-ion collisions with radioactive beams. This article summarizes the main results of the R&D phase, ...devoted to the search for significant improvements of the techniques for charge and mass identification of reaction products. This was obtained by means of a systematic study of the basic detection module, consisting of two transmission-mounted silicon detectors followed by a CsI(Tl) scintillator. Significant improvements in
ΔE
-
E
and pulse-shape techniques were obtained by controlling the doping homogeneity and the cutting angles of silicon and by putting severe constraints on thickness uniformity. Purposely designed digital electronics contributed to identification quality. The issue of possible degradation related to radiation damage of silicon was also addressed. The experimental activity was accompanied by studies on the physics governing signal evolution in silicon. The good identification quality obtained with the prototypes during the R&D phase, allowed us to investigate also some aspects of isospin physics, namely isospin transport and odd-even staggering. Now, after the conclusion of the R&D period, the FAZIA Collaboration has entered the demonstrator phase, with the aim of verifying the applicability of the devised solutions for the realization of a larger-scale experimental set-up.
The next generation of 4π detector arrays for heavy ion studies will largely use Pulse Shape Analysis to push the performance of silicon detectors with respect to ion identification. Energy ...resolution and pulse shape identification capabilities of silicon detectors under prolonged irradiation by energetic heavy ions have thus become a major issue. In this framework, we have studied the effects of irradiation by energetic heavy ions on the response of neutron transmutation doped (nTD) silicon detectors. Sizeable effects on the amplitude and the risetime of the charge signal have been found for detectors irradiated with large fluences of stopped heavy ions, while much weaker effects were observed by punching-through ions. The robustness of ion identification based on digital pulse shape techniques has been evaluated.
The response of silicon-silicon-CsI(Tl) and silicon-CsI(Tl) telescopes to fragments produced in nuclear interactions has been studied. The telescopes were developed within the FAZIA collaboration. ...The capabilities of two methods are compared: (a) the standard ΔE-E technique and (b) the digital Pulse Shape Analysis technique (for identification of nuclear fragments stopped in a single Si-layer). In a test setup, nuclear fragments covering a large range in nuclear charge, mass and energy were detected. They were produced in nuclear reactions induced by a 35A MeV beam of 129Xe impinging on various targets. It was found that the ΔE-E correlations allow the identification of all isotopes up to Z∼25. With the digital Pulse Shape Analysis it is possible to fully distinguish the charge of stopped nuclei up to the maximum available Z (slightly over that of the beam, Z=54).
A Δ
E
-
E
telescope exploiting a single silicon chip for both Δ
E
measurement and scintillation light collection has been tested. It is a Si - CsI (Tl) telescope tailored for mass identification of ...light charged particles and intermediate mass fragments. A procedure based on two different shaping filters allows for extraction of the Δ
E
-
E
information from the single silicon signal. The quality of the obtained fragment identification is expressed in terms of a figure of merit and compared to that of a standard Δ
E
-
E
telescope. The presented configuration could be a good candidate for the basic cell of a large solid angle array of Δ
E
-
E
telescopes, given the reduction in complexity and cost of the front-end electronics.
We present an analytical model for electron self-injection in nonlinear, multidimensional plasma wave excited by short laser pulse in the bubble regime or by short electron beam in the blowout ...regime. In this regimes, which are typical for electron acceleration in the last experiments, the laser radiation pressure or the electron beam charge pushes out background plasma electrons forming a plasma cavity - bubble - with a huge ion charge. The plasma electrons can be trapped in the bubble and accelerated by the plasma wakefields up to very high energies. The model predicts the condition for electron trapping and the trapping cross section in terms of the bubble radius and the bubble velocity. The obtained results are in a good agreement with results of 3D PIC simulations.
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