Matthieu Valette
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View article: Large radial shift experiments in RHIC and their implications for EIC design
Large radial shift experiments in RHIC and their implications for EIC design Open
View article: Gold-gold luminosity increase in RHIC for a beam energy scan with colliding beam energies extending below the nominal injection energy
Gold-gold luminosity increase in RHIC for a beam energy scan with colliding beam energies extending below the nominal injection energy Open
The Beam Energy Scan phase II (BES-II), performed in the Relativistic Heavy Ion Collider (RHIC) from 2019 to 2021, explored the phase transition between quark-gluon plasma and hadronic gas. BES-II exceeded the goal of a fourfold increase i…
View article: Large Radial Shifts in the EIC Hadron Storage Ring
Large Radial Shifts in the EIC Hadron Storage Ring Open
The Electron Ion Collider will collide hadrons in the Hadron Storage Ring (HSR) with ultra-relativistic electrons in the Electron Storage Ring. The HSR design trajectory includes a large radial shift over a large fraction of its circumfere…
View article: Experimental Test of a New Method to Verify Retraction Margins Between Dump Absorbers and Tertiary Collimators at the LHC
Experimental Test of a New Method to Verify Retraction Margins Between Dump Absorbers and Tertiary Collimators at the LHC Open
The protection of the tertiary collimators (TCTs) and the LHC triplet aperture in case of a so-called asynchronous beam dump relies on the correct retraction between the TCTs and the dump region absorbers. A new method to validate this ret…
View article: RHIC Beam Energy Scan Operation with Electron Cooling in 2020
RHIC Beam Energy Scan Operation with Electron Cooling in 2020 Open
RHIC provided Au-Au collisions at beam energies of 5.75 and 4.59 GeV/nucleon for the physics program in 2020 as a part of the Beam Energy Scan II experiment. The operational experience at these energies will be reported with emphasis on th…
View article: RHIC Delayed Abort Experiments
RHIC Delayed Abort Experiments Open
For RHIC to operate at its top energy (100 GeV/n) while protecting the future sPHENIX detector, spontaneous and asynchronous firing of abort kicker modules (pre-fires) have to be avoided. A new triggering circuit for the abort kickers was …
View article: Review of the Fixed Target Operation at RHIC in 2020
Review of the Fixed Target Operation at RHIC in 2020 Open
As part of the Beam Energy Scan (BES) physics program, RHIC operated in Fixed Target mode at various beam energies in 2020. The fixed target experiment, achieved by scraping the beam halo of the circulating beam on a gold ring inserted in …
View article: Electron Ion Collider Machine Protection System: On the necessity of the MPS abort system for Rapid Cycling Synchrotron
Electron Ion Collider Machine Protection System: On the necessity of the MPS abort system for Rapid Cycling Synchrotron Open
The Electron Ion Collider (EIC) accelerator complex includes multiple high-energy high-power accelerators [1]. Operation of such a complex is associated with numerous dangers of possible damage to the equipment. The EIC machine protection …
View article: MD 2935: 16L2 solenoid tests
MD 2935: 16L2 solenoid tests Open
This MD allowed confirming that the solenoid installed in 16L2 during Technical Stop 2 (TS22017) could be held responsible for the performance improvement observed after TS2. The MD was performed on 30th November 2017 in parallel with MD#2…
View article: Machine Protection Experience from Beam Tests with Crab Cavity Prototypes in the CERN SPS
Machine Protection Experience from Beam Tests with Crab Cavity Prototypes in the CERN SPS Open
Crab cavities (CCs) constitute a key component of the High Luminosity LHC (HL-LHC) project. In case of a failure, they can induce significant transverse beam offsets within tens of microseconds, necessitating a fast removal of the circulat…
View article: MD#2889: 16L2 Event Dynamics and UFO Nature Investigation
MD#2889: 16L2 Event Dynamics and UFO Nature Investigation Open
Micrometer sized particles (UFOs) entering the beam are a known cause of localized beam losses since the beginning of high intensity beam operation, however the origin of these particles is not fully known. Furthermore, during 2017 a new t…
View article: Characterisation of the Radiation Hardness of Cryogenic Bypass Diodes for the HL-LHC Inner Triplet Quadrupole Circuit
Characterisation of the Radiation Hardness of Cryogenic Bypass Diodes for the HL-LHC Inner Triplet Quadrupole Circuit Open
The powering layout of the new HL-LHC Nb₃Sn triplet circuits is the use of cryogenic bypass diodes, where the diodes are located inside an extension to the magnet cryostat, operated in superfluid helium and exposed to radiation. Therefore,…
View article: Results of UFO dynamics studies with beam in the LHC
Results of UFO dynamics studies with beam in the LHC Open
Micrometer sized particles entering the LHC beam (the so-called Unidentified Falling Objects or UFOs) are a known cause of localized beam losses since the beginning of high intensity beam operation, however the origin of these particles is…
View article: Safe Disposal of the LHC Beam without Beam Dump: Method and Experimental Verification
Safe Disposal of the LHC Beam without Beam Dump: Method and Experimental Verification Open
In the extremely unlikely event of a non-working beam dumping system in the LHC, the 360 MJ of stored beam energy can be dissipated in the collimation system as a last mitigation measure. In such a situation, it is important to reduce the …
View article: MD#2183: Calibration of the IR6 B2 diamond BLMs
MD#2183: Calibration of the IR6 B2 diamond BLMs Open
In case of an asynchronous beam dump with a fully filled LHC machine, causing ~40 bunches to impact on the movable dump protection absorber (TCDQ), it is expected that all standard ionisation chamber Beam Loss Monitors (IC BLM) around the …
View article: MD#1826: Measurement of Quench Heater vertical kick
MD#1826: Measurement of Quench Heater vertical kick Open
Following the observation of vertical orbit oscillations of the LHC beam between the detection of a (beam induced) quench of an LHC main dipole and the beam dump, a study was started to verify that the orbit distortions are caused by the f…
View article: Beam Loss Measurements for Recurring Fast Loss Events During 2017 LHC Operation Possibly Caused by Macroparticles
Beam Loss Measurements for Recurring Fast Loss Events During 2017 LHC Operation Possibly Caused by Macroparticles Open
The availability of the LHC machine was adversely affected in 2017 by tens of beam aborts provoked by frequent loss events in one standard arc cell (16L2). In most of the cases, the dumps were triggered by concurrently developing fast beam…
View article: Crab Cavity Failures Combined with a Loss of the Beam-Beam Kick in the High Luminosity LHC
Crab Cavity Failures Combined with a Loss of the Beam-Beam Kick in the High Luminosity LHC Open
Crab cavities are an essential component of the High Luminosity LHC (HL-LHC) project. In case of a failure they can create large transverse kicks on the beam within tens of microseconds and, therefore, require a fast extraction of the circ…
View article: Observations, Analysis and Mitigation of Recurrent LHC Beam Dumps Caused by Fast Losses in Arc Half-Cell 16L2
Observations, Analysis and Mitigation of Recurrent LHC Beam Dumps Caused by Fast Losses in Arc Half-Cell 16L2 Open
Recurrent beam dumps significantly perturbed the operation of the CERN LHC in the summer months of 2017, especially in August. These unexpected beam dumps were triggered by fast beam losses that built up in the cryogenic beam vacuum at the…
View article: Impact of Superconducting Magnet Protection Equipment on the Circulating Beam in HL-LHC
Impact of Superconducting Magnet Protection Equipment on the Circulating Beam in HL-LHC Open
The new superconducting quadrupole and dipole magnets for the High Luminosity LHC (HL-LHC) will rely on quench heaters or Coupling-Loss Induced Quench (CLIQ) units or a combination of both to protect the magnet coils in case of a quench. A…
View article: Experimental Setup to Characterize the Radiation Hardness of Cryogenic Bypass Diodes for the HL-LHC Inner Triplet Circuits
Experimental Setup to Characterize the Radiation Hardness of Cryogenic Bypass Diodes for the HL-LHC Inner Triplet Circuits Open
For the high luminosity upgrade of the Large Hadron Collider (LHC), it is planned to replace the existing triplet quadrupole magnets with Nb₃Sn quadrupole magnets, which provide a comparable integrated field gradient with a significantly i…
View article: MD2036: UFO Dynamics Studies and UFO Fast Detection
MD2036: UFO Dynamics Studies and UFO Fast Detection Open
UFOs are one of the remaining unknown related to LHC operation. Therefore, improving the understanding of UFO dynamics and validating the developed models against direct beam measurements is of fundamental importance in view of LHC operati…
View article: MD#1182: Calibration of diamond particle detectors in IP6
MD#1182: Calibration of diamond particle detectors in IP6 Open
In case of an asynchronous beam dump with a fully filled LHC machine it is expected that all standard ionisation chamber Beam Loss Monitors (IC BLM) around the LHC dumping region in IP6 will be saturated. Diamond Beam Loss Monitors (dBLM) …
View article: Requirements for Crab Cavity System Availability in HL-LHC
Requirements for Crab Cavity System Availability in HL-LHC Open
Crab Cavities will be installed in the High Luminosity LHC in order to increase the effective peak luminosity through a partial compensation of the geometric factor. This will allow extending the levelling time resulting in an increased pr…
View article: Lessons Learnt from the 2016 LHC Run and Prospects for HL-LHC Availability
Lessons Learnt from the 2016 LHC Run and Prospects for HL-LHC Availability Open
The LHC exhibited unprecedented availability during the 2016 proton run, producing about 40 fb-1 of integrated luminosity, surpassing the sum of production during the 4 previous years. This was achieved while running steadily with a peak l…
View article: Effect of Quench Heater and CLIQ Firing on the Circulating HL-LHC Beam
Effect of Quench Heater and CLIQ Firing on the Circulating HL-LHC Beam Open
A small vertical orbit oscillation of the LHC beam was observed following a quench of a main dipole magnet. This effect was thought to be caused by the current dis-charged in the quench heater (QH) strips of the superconducting magnet and …
View article: Beam Diagnostics of the LIPAC Injector With a Focus on the Algorithm Developed for Emittance Data Analysis of High Background Including Species Fraction Calculation
Beam Diagnostics of the LIPAC Injector With a Focus on the Algorithm Developed for Emittance Data Analysis of High Background Including Species Fraction Calculation Open
To prove the feasibility of the IFMIF accelerators concept, the EVEDA phase will commission in Japan the LIPAC accelerator, which will deliver a 125 mA/9 MeV CW deuteron beam. LEDA already managed 100 mA in CW at 6.7 MeV in 2000. The diffe…
View article: Advanced Concepts and Methods for Very High Intensity Linacs
Advanced Concepts and Methods for Very High Intensity Linacs Open
For very high intensity linacs, both beam power and space charge should be taken into consideration for any analysis of accelerators aiming at comparing their performances and pointing out the challenging sections. As high beam power is an…
View article: Intermediate Commissioning Results of the 70 mA/50 keV H⁺ and 140 mA/100 keV D⁺ ECR Injector of IFMIF/LIPAC
Intermediate Commissioning Results of the 70 mA/50 keV H⁺ and 140 mA/100 keV D⁺ ECR Injector of IFMIF/LIPAC Open
The LIPAc accelerator aims to operate 125 mA/CW deuteron beam at 9 MeV to validate IFMIF's accelerators that will operate in CW 125 mA at 40 MeV. The different subsystems of LIPAc have been designed and constructed mainly by European labs …
View article: Core-halo Limits and Beam Halo-formation Dynamic
Core-halo Limits and Beam Halo-formation Dynamic Open
In high intensity linear accelerators, space charge related instabilities and effects are the cause of emittance increase and beam losses. The mechanism of halo formation due to a mismatched beam causing parametric resonances and energy tr…