Search results for "Particle accelerator"
showing 10 items of 180 documents
Improving bleeding detector features for electron intraoperative radiotherapy
2019
Abstract Purpose The aim of this work is to improve the potential bleeding detection during intraoperative radiotherapy with linac polymethyl methacrylate applicators (PMMA), based on one previously developed. The improvements carried out have been focused on: i) minimizing the impact of the detector on the visual through the plastic applicators and ii) avoiding the asymmetry in the detection capability when the applicator is tilted. Methods Simulations have been made to select the geometry that provides a reduced visual impact on the applicator as well as allowing an independent response with the tilting angle of the applicator. A low-noise circuit for signal conditioning has been develope…
Ion production from solid state laser ion sources.
2010
Laser ion sources based on resonant excitation and ionization of atoms are well-established tools for selective and efficient production of radioactive ion beams. Recent developments are focused on the use of the state-of-the-art all solid-state laser systems. To date, 35 elements of the periodic table are available from laser ion sources based on tunable Ti:sapphire lasers. Recent progress in this field regarding the establishment of suitable optical excitation schemes for Ti:sapphire lasers are reported.
The effect of gas mixing and biased disc voltage on the preglow transient of electron cyclotron resonance ion source
2012
The effect of gas mixing and biased disc voltage on the preglow of electron cyclotron resonance ion source plasma has been studied with the AECR-U type 14 GHz ion source. It was found that gas mixing has a significant effect on the preglow. The extracted transient beam currents and efficiency of the heavier species increase, while the currents and efficiency of the lighter species decrease when gas mixing is applied. The effect of the biased disc was found to be pronounced in continuous operation mode in comparison to preglow. The data provide information on the time scales of the plasma processes explaining the effects of gas mixing and biased disc. The results also have implications on pr…
Measurement of branching fractions and charge asymmetries for exclusive B decays to charmonium
2005
We report measurements of branching fractions and charge asymmetries of exclusive decays of neutral and charged B mesons into two-body final states containing a charmonium state and a light strange meson. The charmonium mesons considered are J/Psi, Psi(2S) and Chi_c1, and the light meson is either K or K*. We use a sample of about 124 million BBbar events collected with the BABAR detector at the PEP-II storage ring at the Stanford Linear Accelerator Center.
Dosimetry for electron Intra-Operative RadioTherapy: Comparison of output factors obtained through alanine/EPR pellets, ionization chamber and Monte …
2015
Abstract In this work a comparison between the response of alanine and Markus ionization chamber was carried out for measurements of the output factors (OF) of electron beams produced by a linear accelerator used for Intra-Operative Radiation Therapy (IORT). Output factors (OF) for conventional high-energy electron beams are normally measured using ionization chamber according to international dosimetry protocols. However, the electron beams used in IORT have characteristics of dose per pulse, energy spectrum and angular distribution quite different from beams usually used in external radiotherapy, so the direct application of international dosimetry protocols may introduce additional uncer…
Optical spectroscopy and performance tests with a solid state laser ion source at HRIBF
2008
An ISOLDE-type hot-cavity laser ion source based on high-repetition-rate Ti:Sapphire lasers has been set up at the Holifield radioactive ion beam facility. To assess the feasibility of the all-solid-state laser system for applications at advanced radioactive ion beam facilities, spectroscopy and performance tests have been conducted with this source. The results of recent studies on excitation schemes, source efficiency, beam emittance and ion time structure are presented.
Resonant laser ionization mass spectrometry: An alternative to AMS?
2000
Resonant laser ionization mass spectrometry (RIMS) has developed into a versatile experimental method particularly concerning applications for highly selective ultratrace analysis. Apart from providing nearly complete isobaric suppression and high overall efficiency, the possibility for combining optical isotopic selectivity with that of the mass spectrometer leads to remarkable specifications. The widespread analytical potential and applicability of different techniques based on resonant laser ionization is demonstrated in investigations on stable and radioactive ultratrace isotopes with the focus on applications which require high selectivity, concerning, e.g., the noble gas isotopes 81,8…
The REX-ISOLDE project
1998
Abstract REX-ISOLDE [1] is an experiment at ISOLDE/CERN with a twofold aim: (i) to demonstrate a novel efficient scheme for the acceleration of radioactive ions from the online mass separator ISOLDE to energies around the Coulomb barrier. (ii) to perform first nuclear physics experiments by studying the structure of the neutron-rich (N = 20, N = 28) nuclei by Coulomb excitation and neutron transfer reactions. An overview on the different components of the radioactive beam accelerator is given with special emphasis on the separation possibilities and ion number capabilities of the system.
Vacuum electrical breakdown conditioning study in a parallel plate electrode pulsed dc system
2019
Conditioning of a metal structure in a high-voltage system is the progressive development of resistance to vacuum arcing over the operational life of the system. This is, for instance, seen during the initial operation of radio frequency (rf) cavities in particle accelerators. It is a relevant topic for any technology where breakdown limits performance and where conditioning continues for a significant duration of system run time. Projected future linear accelerators require structures with accelerating gradients of up to 100 MV/m. Currently, this performance level is achievable only after a multimonth conditioning period. In this work, a pulsed dc system applying voltage pulses over paral…
Electron Ion Collider: The Next QCD Frontier - Understanding the glue that binds us all
2016
This White Paper presents the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader nuclear science community. It was commissioned by the managements of Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility (JLab) with the objective of presenting a summary of scientific opportunities and goals of the EIC as a follow-up to the 2007 NSAC Long Range plan. This document is a culmination of a community-wide effort in nuclear science following a series of workshops on EIC physics and, in particular, the focused ten-week program on "Gluons and quark sea a…