Search results for "accelerator"
showing 10 items of 1507 documents
Conceptual Design and Modeling of Fast Discharge Unit for Quench Protection of Superconducting Toroidal Field Magnets of DTT
2020
The paper deals with the modelling and simulation of a Fast Discharge Unit (FDU) for quench protection of the Toroidal Field (TF) magnets of the Divertor Tokamak Test, an experimental facility under design and construction in Frascati (Italy). The FDU is a safety key component that protects the superconducting magnets when a quench is detected through the fast extraction of the energy stored in superconducting magnets by adding in the TF magnets a dump (or discharge) resistor. In the paper, two different configurations of dump resistors (fixed and variable respectively) have been analysed and discussed. As a first result, it is possible to underline that the configuration with variable dump…
Cross-section-constrained top-quark mass measurement from dilepton events at the tevatron
2008
We report the first top quark mass measurement that uses a cross section constraint to improve the mass determination. This measurement is made with a dilepton $t\bar{t}$ event sample collected with the CDF II detector. From a data sample corresponding to an integrated luminosity of 1.2 fb$^{-1}$, we measure a top quark mass of $\rm{170.7^{+4.2}_{-3.9}(stat)\pm2.6(syst)}$ $\rm{\pm2.4(theory) GeV/{\it{c}}^{2}}$. The measurement without the cross section constraint results in a top quark mass of $\rm{169.7^{+5.2}_{-4.9}(stat)\pm3.1(syst) GeV/{\it{c}}^{2}}$.
First measurement of the forward-backward charge asymmetry in top quark pair production
2008
We present the first measurement of the integrated forward-backward charge asymmetry in top-antitop quark pair (ttbar) production in proton-antiproton collisions in the lepton plus jets final state. Using a b-jet tagging algorithm and kinematic reconstruction assuming ttbar+X production and decay, a sample of 0.9fb-1 of data, collected by the D0 experiment at the Fermilab Tevatron Collider, is used to measure the asymmetry for different jet multiplicities. The result is also used to set upper limits on ttbar+X production via a Z' resonance.
Combination of D0 measurements of the top quark mass
2017
We present a combination of measurements of the top quark mass by the D0 experiment in the lepton+jets and dilepton channels. We use all the data collected in Run I (1992--1996) at $\sqrt s=1.8$ TeV and Run II (2001--2011) at $\sqrt s=1.96$ TeV of the Tevatron $p \bar{p}$ collider, corresponding to integrated luminosities of 0.1 fb$^{-1}$ and 9.7 fb$^{-1}$, respectively. The combined result is: $m_t = 174.95 \pm0.40\,{\rm(stat)} \pm 0.64\,{\rm(syst)}\,{\rm{GeV}}=174.95 \pm 0.75 \, {\rm{GeV}}$.
Precise measurement of the top quark mass in dilepton decays using optimized neutrino weighting
2016
We measure the top quark mass in dilepton final states of top-antitop events in proton-antiproton collisions at sqrt(s) = 1.96 TeV, using data corresponding to an integrated luminosity of 9.7 fb^-1 at the Fermilab Tevatron Collider. The analysis features a comprehensive optimization of the neutrino weighting method to minimize the statistical uncertainties. We also improve the calibration of jet energies using the calibration determined in top-antitop to lepton+jets events, which reduces the otherwise limiting systematic uncertainty from the jet energy scale. The measured top quark mass is mt = 173.32 +/- 1.36(stat) +/- 0.85(syst) GeV.
Status of the SHIPTRAP Project: A Capture and Storage Facility for Heavy Radionuclides from SHIP
2001
The ion trap facility SHIPTRAP is being set up to deliver very clean and cool beams of singly-charged recoil ions produced at the SHIP velocity filter at GSI Darmstadt. SHIPTRAP consists of a gas cell for stopping and thermalizing high-energy recoil ions from SHIP, an rf ion guide for extraction of the ions from the gas cell, a linear rf trap for accumulation and bunching of the ions, and a Penning trap for isobaric purification. The progress in testing the rf ion guide is reported. A transmission of about 93(5)% was achieved.
Thermal Design of Refridgerated Hexapole 18 GHZ ECRIS HIISI
2014
A project is underway for constructing a new 18 GHz ECR ion source HIISI at University of Jyväskylä. An innovative plasma chamber structure with grooves at magnetic poles for larger chamber radius at poles. The hexapole will be refridgerated to sub-zero temperatures to boost the coercivity and the remanence of the permanent magnet material and to allow the use of high remanence, low intrinsic coersivity permanent magnet materials. The hexapole structure is insulated from high temperature solenoid coils and plasma chamber by vacuum. The thermal design of the structure has been made using a thermal diffusion code taking in account radiative, conductive and convective heat transfer processes. …
HIISI, New 18 GHZ ECRIS for the JYFL Accelerator Laboratory
2014
At the end of 2013 the Academy of Finland granted an infrastructure funding for the JYFL Accelerator Laboratory in order to increase beam intensities for the international user community. The primary objective is to construct a new high performance ECR ion source, HIISI (Heavy Ion Ion Source Injector), for the K130 cyclotron. Using room temperature magnets the HIISI has been designed to produce about the same magnetic field configuration as the superconducting ECRIS SUSI at NSCL/MSU for 18 GHz operation. An innovative structure will be used to maximize the radial confinement and demagnetization safety margin of the permanent magnets. The sextupole magnet is separated and insulated from the …
Status of new 18 GHz ECRIS HIISI
2018
A new 18 GHz ECR ion source HIISI is under commissioning at the Accelerator Laboratory at the University of Jyväskylä (JYFL). The main purpose of HIISI is to produce high-energy beam cocktails, e.g. Xe44+, for radiation effects testing of electronics with the K130 cyclotron. The initial commissioning results in 18+14 GHz operation with oxygen, argon and xenon are reported. The beam currents are compared to those produced by reference ion sources (JYFL 14 GHz ECRIS, GTS and SuSI). At the moment (October 2017) 560 µA of O6+ and 310 µA of Ar13+, for example, have been reached with HIISI at 2.3 kW total power. peerReviewed
Status of new 18 GHz ECRIS HIISI
2018
A new 18 GHz ECR ion source HIISI is under commissioning at the Accelerator Laboratory at the University of Jyvaskyla (JYFL). The main purpose of HIISI is to produce high-energy beam cocktails, e.g. Xe44+, for radiation effects testing of electronics with the K130 cyclotron. The initial commissioning results in 18+14 GHz operation with oxygen, argon and xenon are reported. The beam currents are compared to those produced by reference ion sources (JYFL 14 GHz ECRIS, GTS and SuSI). At the moment (October 2017) 560 µA of O6+ and 310 µA of Ar13+, for example, have been reached with HIISI at 2.3 kW total power.A new 18 GHz ECR ion source HIISI is under commissioning at the Accelerator Laboratory…