E8 Quiver Gauge Theory and Mirror Symmetry

We show that the Higgs branch of a four-dimensional Yang-Mills theory, with gauge and matter content summarised by an E_8 quiver diagram, is identical to the generalised Coulomb branch of a four-dimensional superconformal strongly coupled gauge theory with E_8 global symmetry. This is the final step in showing that there is a Higgs-Coulomb identity of this kind for each of the cases {0}, A_1, A_2, D_4, E_6, E_7 and E_8. This series of equivalences suggests the existence of a mirror symmetry between the quiver theories and the strongly coupled theories. We also discuss how to interpret the parameters of the quiver gauge theory in terms of the Hanany-Witten picture.Comment: 19 pages, 3 figures, references adde

Collimation performance of the 400MJ LHC beam at 6.8 TeV

During the third operational run of the Large Hadron Collider at CERN, starting in 2022, the beam energy was increased to 6.8 TeV and the bunch population is planned to be pushed to unprecedented levels. Already in the first year of operation, stored beam energies up to 400 MJ were achieved. An improvement in cleaning performance of the LHC collimation system is hence required. In this paper we review the collimation system performance during 2022, and compare it to previous years. Particular attention is given to the performance during beta*-levelling, which is part of the nominal cycle in Run 3. The performance of the automatic alignment tools is also discussed. Finally, we review the stability of the collimation system, which was monitored regularly during the run for all machine configurations to ensure the continued adequate functionality of the system

The human secretome

The proteins secreted by human cells (collectively referred to as the secretome) are important not only for the basic understanding of human biology but also for the identification of potential targets for future diagnostics and therapies. Here, we present a comprehensive analysis of proteins predicted to be secreted in human cells, which provides information about their final localization in the human body, including the proteins actively secreted to peripheral blood. The analysis suggests that a large number of the proteins of the secretome are not secreted out of the cell, but instead are retained intracellularly, whereas another large group of proteins were identified that are predicted to be retained locally at the tissue of expression and not secreted into the blood. Proteins detected in the human blood by mass spectrometry-based proteomics and antibody-based immuno-assays are also presented with estimates of their concentrations in the blood. The results are presented in an updated version 19 of the Human Protein Atlas in which each gene encoding a secretome protein is annotated to provide an open-access knowledge resource of the human secretome, including body-wide expression data, spatial localization data down to the single-cell and subcellular levels, and data about the presence of proteins that are detectable in the blood

Criticality of fast failures in the High Luminosity Large Hadron Collider

Each of the two Large Hadron Collider (LHC) beams contain 362 MJ of energy. This will be further increased to 678 MJ in the upcoming upgrade to the High Luminosity LHC (HL-LHC). In the event of an uncontrolled beam loss, a significant hazard occurs, that can damage the machine components. This thesis is focused on failures that can lead to a fast increase of beam losses, with a focus on the new optics and equipment in the HL-LHC. The criticality for a number of failure scenarios is studied, under different optics configurations of the machine. Mitigation strategies, involving dedicated interlocking and a reduction of the impact that the failures have on the beam are proposed for the most critical scenarios. For a number of less critical failures it is determined that current interlock strategies are sufficient. Failures involving the magnet protection and the crab cavities constitute the most severe hazards. The former consists of quench heaters and a new system known as coupling loss induced quench (CLIQ). A new connection scheme is proposed for these, in order to limit their effect on the beam. Dedicated interlocks for detecting spurious discharges of these systems are also found to be necessary. The perturbation of the beam orbit caused by the extraction of only one beam is another source of uncontrolled beam losses. A fast hardware linking of the two beams to limit the delay between extracting the two beams of maximum one LHC turn (89 µs) is found to be necessary. Beam-dust interactions have detrimental effects on the machine performance and availability. Advances are made on the understanding of their dynamics through dedicated experiments combined with theoretical work and simulations. Superconducting magnet quenches are shown capable of causing fast orbit perturbations. The effects of beam-beam compensating wires as well as coherent excitations by the transverse beam damper are also discussed. Finally, realistic combinations of multiple failures are also discussed

A novel diamond-based beam position monitoring system for the High Radiation to Materials facility at CERN SPS

The High Radiation to Materials facility employs a high intensity pulsed beam imposing several challenges on the beam position monitors. Diamond has been shown to be a resilient material with its radiation hardness and mechanical strength, while it is also simple due to its wide bandgap removing the need for doping. A new type of diamond based beam position monitor has been constructed, which includes a hole in the center of the diamond where the majority of the beam is intended to pass through. This increases the longevity of the detectors as well as allowing them to be used for high intensity beams. The purpose of this thesis is to evaluate the performance of the detectors in the High Radiation to Materials facility for various beam parameters, involving differences in position, size, bunch intensity and bunch number. A prestudy consisting of calibration of the detectors using single incident particles is also presented. The detectors are shown to work as intended after a recalibration of the algorithm, albeit with a slightly lower precision than requested, giving a promising new beam position monitoring system. They work for the full intensity range and a single bunch resolution is achieved. Functionality is also shown with backscattering from dense targets

MD#2183: Calibration of the IR6 B2 diamond BLMs

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 LHC dumping region in IR6 will be saturated. Diamond Beam Loss Monitors (dBLM) were therefore installed next to the TCDQ downstream of the extraction kickers. These detectors allow resolving losses at a nanosecond timescale and with a dynamic range of several orders of magnitude; thus, allowing to derive the number of nominal bunches impacting the TCDQ. After a first series of calibrations using asynchronous beam dump tests, an experiment was conducted during MD#1182 to demonstrate the possibility of resolving a nominal bunch hitting the TCDQ. During this first MD only the Beam 1 dBLM was calibrated appropriately, a second calibration MD was therefore performed in 2017 for the B2 system. Results from this MD and conclusions regarding dBLM saturation with a top energy nominal bunch are discussed in this note, which also includes results from MD#2930

MD#1182: Calibration of diamond particle detectors in IP6

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) were therefore installed next to the movable dump protection absorber (TCDQ) downstream of the extraction kickers. These detectors allow resolving losses at a nanosecond timescale and with an dynamic range of several orders of magnitude; thus, allowing to know the number of nominal bunches impacting the TCDQ. After a first series of calibrations using asynchronous beam dump tests, an experiment was conducted during MD#1182 to demonstrate the possibility of resolving a nominal bunch hitting the TCDQ. The impact parameter of the bunches on the TCDQ was first scanned using probe bunches with lower intensity then tests were done with nominal bunches (1.1e11 p/bunch) at injection energy. High energy calibration of the losses was also attempted unsuccessfully. Due to different behaviour in observed in B1 and B2 an inspection in the LHC tunnel was performed. The analysis results and prospects for future MDs are presented below

MD 3246: 16L2 UFO dynamics investigations

Micrometer sized particles (UFOs) entering the beam are a known cause of localized beam losses since the beginning of high intensity beam operations, however the origin of these particles is not fully known. Furthermore, during 2017 a new type of UFO events appeared around the 16L2 interconnection in the LHC, leading to beam instabilities resulting in a major impact on beam availability. In MD#2889 these 16L2 UFOs were studied with the help of very fast diamond beam loss monitors (dBLM) that were installed at the source of the UFOs, providing important data on the dynamics of the UFOs. However, only one event could be recorded. In order to acquire more data, and of better quality using the significantly improved data acquisition system, this MD was executed. The MD was done in parallel with MD2484. and the procedure was adjusted for both MDs to profit as much as possible. The UFO part of the MD was split into two parts; one with a small number of blown-up bunches as not to negatively impact the other MD, and lastly one EOF where a large number of bunches were to be blown-up and a 16L2 event was to be provoked, however the beams were dumped at the start of the blow-up. One small event was recorded during the first part of the MD

MD#1826: Measurement of Quench Heater vertical kick

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 firing of the quench heaters (QH). Simulation of the magnetic field generated by the discharge of the QH and its effect on the beam confirmed it was the most likely cause. A dedicated experiment with 450 GeV proton beams was performed to validate the simulation results. The results are presented below and compared to the simulations. Furthermore, estimates on the effect of quench heater firing in superconducting magnets other than the studied LHC main dipoles on the circulating proton beams in LHC and the future HL-LHC are discussed

MD2036: UFO Dynamics Studies and UFO Fast Detection

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 operation at 7 TeV and with HL-LHC beam intensities. If not understood, UFOs could also be a showstopper for future machines such as FCC. This MD demonstrates new methods to study the dynamic behaviour of a calibrated UFO, simulated by the interaction of wire scanners with the beam. The events created during the MD were monitored using diamond BLMs in IR7, providing bunch-by-bunch resolution measurements. The analysis presented herein shows that blown-up bunches can be used to identify the plane of movement of UFOs, that bunch profiles and bunch sizes can be measured with dBLMs with good precision, that simulation of expected losses are in good agreement with measurements for oscillating bunches and that the space resolution of the acquisition system used during the MD is about 10 um