| Paper | Title | Page |
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| WEPMP031 | SPS Slow Extraction Losses and Activation: Update on Recent Improvements | 2391 |
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Annual high intensity requests of over 1019 protons on target (POT) from the CERN Super Proton Synchrotron (SPS) Fixed Target (FT) physics program continue, with the prospect of requests for even higher, unprecedented levels in the coming decade. A concerted and multifaceted R&D effort has been launched to understand and reduce the slow extraction induced radioactivation of the SPS and to anticipate future experimental proposals, such as SHiP* at the SPS Beam Dump Facility (BDF)**, which will request an additional 4·1019 POT per year. In this contribution, we report on operational improvements and recent advances that have been made to significantly reduce the slow extraction losses, by up to a factor of 3, with the deployment of new extraction concepts, including passive and active (thin, bent crystal) diffusers and extraction on the third-integer resonance with octupoles. In light of the successful tests of the prototype extraction loss reduction schemes, an outlook and implications for future SPS FT operation will be presented.
* A. Golutvin et al., Rep. CERN-SPSC-2015-016 (SPSC-P-350), CERN, Geneva, Switzerland, Apr. 2015. ** M. Lamont et al., Rep. CERN-PBC-REPORT-2018-001, CERN, Geneva, Switzerland, 11 Dec 2018. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP031 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| THPGW061 | The K12 Beamline for the KLEVER Experiment | 3726 |
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| The KLEVER experiment is proposed to run in the CERN ECN3 underground cavern from 2026 onward. The goal of the experiment is to measure BR(KL -> pi0 nu nu), which could yield information about potential new physics, by itself and in combination with the measurement of BR(K+ -> pi+ nu nu) of NA62. A full description will be given of the considerations in designing the new K12 beamline for KLEVER, as obtained from a purpose made simulation with FLUKA. The high intensities required by KLEVER, 2·1013 protons on target every 16.8s, with 5·1019 protons accumulated over 5~years, place stringent demands on adequate muon sweeping to minimize backgrounds in the detector. The target and primary dump need to be able to survive these demanding conditions, while respecting strict radiation protection criteria. A series of design choices will be shown to lead to a neutral beamline sufficiently capable of suppressing relevant backgrounds, such as photons generated by pi0 decays in the target, and Lambda -> npi0 decays, which mimic the signal decay. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW061 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| THPGW062 | The New CERN East Area Primary and Secondary Beams | 3730 |
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| The East Area is one of the intensely used facilities at CERN, now serving for over 56 years beams to more than 20 user teams and experiments for about 200 days of running each year. Besides primary proton and ion beams for the irradiation facilities IRRAD and CHARM, mixed secondary beams of hadrons, electrons and muons within a range of 0.5 GeV/c to 12 GeV/c are provided. The CERN management approved an upgrade and renovation of the full facility to meet reliably future beam test and physics requirements. We present new, flexible beam optics that will assure better purity of the secondary beams, even with the new possibility of highly pure electron, hadron or muon beams. The upgrade also includes a pulsed powering scheme with energy recovering power supplies and new laminated magnets that will reduce both power and cooling requirements. The renovation phase started already and first beams in the new facility will be delivered from 2021 on. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW062 | |
| About • | paper received ※ 03 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| THPGW063 | The "Physics Beyond Colliders" Projects for the CERN M2 Beam | 3734 |
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| Physics Beyond Colliders is an exploratory study aimed at exploiting the full scientific potential of CERN’s accelerator complex up to 2040 and its scientific infrastructure through projects complementary to the existing and possible future colliders. Within the Conventional Beam Working Group (CBWG), several pro-jects for the M2 beam line in the CERN North Area were proposed, such as a successor for the COMPASS experiment, a muon programme for NA64 dark sector physics, and the MuonE proposal aiming at investigating the hadronic contribution to the vacuum polarisation. We present integration and beam optics studies for 100-160 GeV/c muon beams as well as an outlook for improvements on hadron beams, which include RF-separated options and low-energy antiproton beams and radiation studies for high intensity beams. In addition, necessary beam instrumentation upgrades for beam particle identification and momentum measurements are discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW063 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| THPRB083 | Detailed Analysis Of The Baseline Dose Levels And Localized Radiation Spikes In The Arc Sections Of The Large Hadron Collider During Run 2 | 4009 |
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| The Large Hadron Collider (LHC) has eight insertion regions (IRs) which house the large experiments or accelerator equipment. These IRs are interconnected with the arc sections consisting of a periodic magnet structure. During the operation of the LHC small amounts of the beam particles are lost, creating prompt radiation fields in the accelerator tunnels and the adjacent caverns. One of the main loss mechanisms in the LHC arc sections is the interaction of the beam particles with the residual gas molecules. The analysis of the dose levels based on the beam loss measurement data shows that the majority of the measurements have similar levels, which allow to define baseline values for each arc section. The baseline levels decreased during the years 2015, 2016 and stabilised in 2017 and 2018 at annual dose levels below 50 mGy, which can be correlated with the residual gas densities in the LHC arcs. In some location of the arcs radiation spikes exceed the base line by more than two orders of magnitude. In addition to the analysis of these dose levels, a novel approach of identifying local dose maxima and the main driving mechanisms creating these radiation spikes will be presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB083 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| THPRB084 | Run 2 Prompt Dose Distribution and Evolution at the Large Hadron Collider and Implications for Future Accelerator Operation | 4013 |
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| During the operation of the Large Hadron Collider (LHC) small fractions of beam particles are lost, creating prompt radiation fields in the accelerator tunnels. Exposed electronics and accelerator components show lifetime degradation and stochastic Single Event Effects (SEEs) which can lead to faults and downtime of the LHC. Close to the experiments the radiation levels scale nicely with the integrated luminosity since the luminosity debris is the major contributor for creating the radiation fields in this area of the LHC. In the collimation regions it was expected that the radiation fields scale with the integrated beam intensities since the beams are continuously cleaned from particles which exceed the accelerator’s acceptance. The analysis of radiation data shows that the dose measurements in the collimation regions normalised with the integrated beam intensities for 2016 and 2017 are comparable. Against expectations, the intensity normalised radiation datasets of 2018 in these regions differ significantly from the previous years. Especially in the betatron collimation region the radiation levels are up to a factor 3 higher. The radiation levels in the collimation regions correlate with the levelling of beta-star and the crossing angle in the high luminosity experiments ATLAS and CMS. These increased normalised doses have direct implications on the expected dose levels during future LHC operation, including the High-Luminosity LHC (HL-LHC) upgrade. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB084 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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