One of the important factors in high radiation generation facilities is the production of a high quality electron beam. To do that, the requirements of an optical electron source, such as current, ...radiation emission, etc. must be met. For this purpose, cavity beam dynamics studies of 1.4, 1.5, 1.6 and 1.8-cell SRF gun were performed. In addition, detailed studies have been made on the solenoid design and the location of the solenoid along the beam path. A design with the most optimized cavity geometry and RF fields for the gun cavity was posed. The injector system was designed for the Turkish SASE-FEL project with cavities of many different geometrical sizes. The most efficient high energy cavity system is determined as 1.6-cell cavity. The emittance value of the beam was achieved as 1.76±0.42π mm mrad and the beam energy reached at the end of cavity was obtained as 3.5MeV.
•Beam dynamics simulation studies have been carried out for the SRF gun system in cavities with 1.4, 1.5, 1.6 and 1.8 cells.•Astra and CST Codes were utilized to perform beam dynamic simulations and comparisons are made for all half-cell SRF cavities in many aspects to obtain optimized beam.•Simulation results of two programs are agree with each other.•Effects of the solenoid on the beam dynamics have been monitored and detailed.•Simulation results of the Superfish/Poisson and CST simulations were compared.
Designs and simulations of 1.4, 1.5, 1.6, and 1.8-cell SRF gun cavities are studied at a linear accelerator gun system and they are compared with each other. We obtain high power beam from high ...energy electron beam produced at a photocathode with high quantum efficiency, high average current laser with high brightness, and high accelerating gradient. Beam energy of the whole accelerator system is effected mainly by the optimized RF power usage inside cells, the RF power interaction with particle beams, and the accelerated beam obtained by using SRF-gun cells. Thus, the optimized beam parameters, the RF parameters, and the accelerator gun cavity parameters that depend on each cavity geometries of SRF gun are obtained and presented in this paper. Additionally, the energy values of the electrons with optimized emittance at the gun exit are achieved and shown. We will conclude our paper by giving the gun output energies specifying which elliptical cavity-cell geometry is more appropriate to push the beam further in consistent conditions. For the cavity electromagnetic fields and the geometric designs of the cavities and the solenoid, we have utilized 2D Superfish/Poisson and 3D Computer Simulation Technology Programs. Also beam dynamics studies are included for only 1.6-cell SRF gun cavity which has the highest quality factor in order to figure out how the beam behaves along the beamline at the gun system. Transverse emittance (< 2 π mm mrad) and beam energy (∼3.5 MeV) at the exit of the gun system are obtained as expected.
•SC gun cavities are designed and electron beam dynamics are simulated in gun system.•Electromagnetic field behavior inside the cavities is modeled.•Four half-cell gun cavities are designed and one is chosen for the beam dynamics.•Peak electric and magnetic fields on the SC cavity surface are obtained.•Electron beams are traced until the end of the gun system.
First look at the physics case of TLEP Bicer, M.; Duran Yildiz, H.; Coignet, G. ...
The journal of high energy physics,
01/2014, Letnik:
2014, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A
bstract
The discovery by the ATLAS and CMS experiments of a new boson with mass around 125 GeV and with measured properties compatible with those of a Standard-Model Higgs boson, coupled with the ...absence of discoveries of phenomena beyond the Standard Model at the TeV scale, has triggered interest in ideas for future Higgs factories. A new circular e
+
e
−
collider hosted in a 80 to 100 km tunnel, TLEP, is among the most attractive solutions proposed so far. It has a clean experimental environment, produces high luminosity for top-quark, Higgs boson, W and Z studies, accommodates multiple detectors, and can reach energies up to the
threshold and beyond. It will enable measurements of the Higgs boson properties and of Electroweak Symmetry-Breaking (EWSB) parameters with unequalled precision, offering exploration of physics beyond the Standard Model in the multi-TeV range. Moreover, being the natural precursor of the VHE-LHC, a 100 TeV hadron machine in the same tunnel, it builds up a long-term vision for particle physics. Altogether, the combination of TLEP and the VHE-LHC offers, for a great cost effectiveness, the best precision and the best search reach of all options presently on the market. This paper presents a first appraisal of the salient features of the TLEP physics potential, to serve as a baseline for a more extensive design study.
We study start-to-end simulation of the proposed Turkish Accelerator Center (TAC) Self Amplified Spontaneous Emission (SASE) Free Electron Laser (FEL) Facility. Astra Code is used to simulate the ...electron gun, including space charge effects and Elegant Code is used to track particle distribution from the accelerator modules through the entrance of the undulator including weak fields but not including space charge effects. Undulator optimization is performed using Genesis 1.3. In this study, tentative electron beam and laser parameters of the SASE FEL Facility are given.
Design and simulation of a superconducting gun cavity with 3½ cells have been studied in order to give the first push to the electron beam for the linear accelerating system at The Institute of ...Accelerator Technologies at Ankara University. Electrons are accelerated through the gun cavity with the help of the Radiofrequency power suppliers from cryogenic systems. Accelerating gradient should be as high as possible to accelerate electron beam inside the cavity. In this study, electron beam reaches to 9.17MeV energy at the end of the gun cavity with the accelerating gradient; Ec=19.21MV/m. 1.3GHz gun cavity consists of three TESLA-like shaped cells while the special designed gun-cell includes a cathode plug. Optimized important beam parameters inside the gun cavity, average beam current 3mA, transverse emittance 2.5mmmrad, repetition rate 30MHz and other parameters are obtained for the SASE-FEL System. The Superfish/Poisson program is used to design each cell of the superconducting cavity. Superconducting gun cavity and Radiofrequency properties are studied by utilizing 2D Superfish/Poisson, 3D Computer Simulation Technology Microwave Studio, and 3D Computer Simulation Technology Particle Studio. Superfish/Poisson is also used to optimize the geometry of the cavity cells to get the highest accelerating gradient. The behavior of the particles along the beamline is included in this study. ASTRA Code is used to track the particles.
The response of the ATLAS detector to large-radius jets is measured in situ using 36.2 fb
-
1
of
s
=
13
TeV proton–proton collisions provided by the LHC and recorded by the ATLAS experiment during ...2015 and 2016. The jet energy scale is measured in events where the jet recoils against a reference object, which can be either a calibrated photon, a reconstructed
Z
boson, or a system of well-measured small-radius jets. The jet energy resolution and a calibration of forward jets are derived using dijet balance measurements. The jet mass response is measured with two methods: using mass peaks formed by
W
bosons and top quarks with large transverse momenta and by comparing the jet mass measured using the energy deposited in the calorimeter with that using the momenta of charged-particle tracks. The transverse momentum and mass responses in simulations are found to be about 2–3% higher than in data. This difference is adjusted for with a correction factor. The results of the different methods are combined to yield a calibration over a large range of transverse momenta
(
p
T
)
. The precision of the relative jet energy scale is 1–2% for
200
GeV
<
p
T
<
2
TeV
, while that of the mass scale is 2–10%. The ratio of the energy resolutions in data and simulation is measured to a precision of 10–15% over the same
p
T
range.
The production of a W boson in association with a single charm quark is studied using 140 fb - 1 of s = 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron ...Collider. The charm quark is tagged by the presence of a charmed hadron reconstructed with a secondary-vertex fit. The W boson is reconstructed from the decay to either an electron or a muon and the missing transverse momentum present in the event. The charmed mesons reconstructed are D + → K - π + π + and D * + → D 0 π + → ( K - π + ) π + and the charge conjugate decays in the fiducial regions where p T ( e , μ ) > 30 GeV , | η ( e , μ ) | < 2.5 , p T ( D ( * ) ) > 8 GeV , and | η ( D ( * ) ) | < 2.2 . The integrated and normalized differential cross sections as a function of the pseudorapidity of the lepton from the W boson decay, and of the transverse momentum of the charmed hadron, are extracted from the data using a profile likelihood fit. The measured total fiducial cross sections are σ fid OS - SS ( W - + D + ) = 50.2 ± 0.2 ( stat ) - 2.3 + 2.4 ( syst ) pb , σ fid OS - SS ( W + + D - ) = 48.5 ± 0.2 ( stat ) - 2.2 + 2.3 ( syst ) pb , σ fid OS - SS ( W - + D * + ) = 51.1 ± 0.4 ( stat ) - 1.8 + 1.9 ( syst ) pb , and σ fid OS - SS ( W + + D * - ) = 50.0 ± 0.4 ( stat ) - 1.8 + 1.9 ( syst ) pb . Results are compared with the predictions of next-to-leading-order quantum chromodynamics calculations performed using state-of-the-art parton distribution functions. Additionally, the ratio of charm to anticharm production cross sections is studied to probe the s - s ¯ quark asymmetry. The ratio is found to be R c ± = 0.971 ± 0.006 ( stat ) ± 0.011 ( syst ) . The ratio and cross-section measurements are consistent with the predictions obtained with parton distribution function sets that have a symmetric s - s ¯ sea, indicating that any s - s ¯ asymmetry in the Bjorken- x region relevant for this measurement is small.
A search for nonresonant Higgs boson pair production in the b¯bb¯b final state is presented. The analysis uses 126 fb−1 of pp collision data at √s=13 TeV collected with the ATLAS detector at the ...Large Hadron Collider, and targets both the gluon-gluon fusion and vector-boson fusion production modes. No evidence of the signal is found and the observed (expected) upper limit on the cross section for nonresonant Higgs boson pair production is determined to be 5.4 (8.1) times the Standard Model predicted cross section at 95% confidence level. Constraints are placed on modifiers to the HHH and HHVV couplings. The observed (expected) 2σ constraints on the HHH coupling modifier, κλ, are determined to be −3.5,11.3 (−5.4,11.4), while the corresponding constraints for the HHVV coupling modifier, κ2V, are −0.0,2.1 (−0.1,2.1). In addition, constraints on relevant coefficients are derived in the context of the Standard Model effective field theory and Higgs effective field theory, and upper limits on the HH production cross section are placed in seven Higgs effective field theory benchmark scenarios.
Higgs boson production via gluon-gluon fusion and vector-boson fusion in proton-proton collisions is measured in the H → WW *→ eνμν decay channel. The Large Hadron Collider delivered proton-proton ...collisions at a center-of-mass energy of 13 TeV between 2015 and 2018, which were recorded by the ATLAS detector, corresponding to an integrated luminosity of 139 fb −1 . The total cross sections for Higgs boson production by gluon-gluon fusion and vector-boson fusion times the H → WW* branching ratio are measured to be 12.0±1.4 and <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?0.75_%7B-0.16%7D%5E%7B+0.19%7D" data-classname="equation" /> pb, respectively, in agreement with the Standard Model predictions of 10.4±0.6 and 0.81±0.02 pb. Higgs boson production is further characterized through measurements of Simplified Template Cross Sections in a total of 11 kinematic fiducial regions.
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