Studies of Space Charge Effects in the Proposed CERN PS2

A new proton synchrotron, the PS2, is under design study to replace the current proton synchrotron at CERN for the LHC upgrade. Nonlinear space charge effects could cause significant beam emittance growth and particle losses and limit the performance of the PS2. In this paper, we report on studies of the potential spacecharge effects at the PS2 using three-dimensional selfconsistent macroparticle tracking codes, IMPACT, MaryLie/IMPACT, and Synergia. We will present initial benchmark results among these codes. Effects of spacecharge on the emittance growth, especially due to synchrotron coupling, aperture sizes, initial painted distribution, and RF ramping scheme will also be discusse

Studies of Space Charge Effects in the Proposed CERN PS2

A new proton synchrotron, the PS2, is under design study to replace the current proton synchrotron at CERN for the LHC upgrade. Nonlinear space charge effects could cause significant beam emittance growth and particle losses and limit the performance of the PS2. In this paper, we report on studies of the potential space-charge effects at the PS2 using three-dimensional self-consistent macroparticle tracking codes, IMPACT, MaryLie/IMPACT, and Synergia. We will present initial benchmark results among these codes. Effects of space-charge on the emittance growth, especially due to synchrotron coupling, aperture sizes, initial painted distribution, and RF ramping scheme will also be discussed

Polarimetery for SuperB

We provide an overview description of a Compton polarimeter for measuring electron beam polarization near the IR in the Low Energy Ring of SuperB. The polarimeter is designed to achieve 1.0% accuracy. A scheme for measuring the electron beam polarization at SuperB near the IR has been described. The Compton polarimeter has been designed to fit into the existing lattice of the SuperB ring and results in a Compton IP measuring the polarization located where the beam is almost longitudinal with opposite helicity to that at the IR. The polarization at the IR is expected to be determined with an accuracy of {approx}1% from the measurement at the Compton IP provided the beam direction at the electron-positron interaction region and the Compton IP are well known and the beam energy is measured to better than 20 MeV. Detailed detector studies are needed to study resolution and acceptance effects on detector analyzing powers, and to determine sensitivity to beam and machine parameters

Constraints on the FCC-ee Lattice from the Compatibility with the FCC Hadron Collider

Following the recommendations of the European Strategy Group for High Energy Physics, CERN started the Future Circular Collider Study (FCC), a design study for possible future circular collider projects to investigate their feasibility for high energy physics research. The FCC Study covers three different machines with a circumference of 100 km: an electron positron collider with collision energy in the range of 91 GeV to 350 GeV (FCC-ee), a proton proton collider with a maximum energy of 100 TeV (FCC-hh) and an electron proton option (FCC-he). This talk will point out the constraints on the design of the FCC-ee lattice and optics from geometry and lattice considerations of the hadron machine

Combined Operation and Staging Scenarios for the FCC-ee Lepton Collider

FCC-ee is a proposed high-energy electron positron circular collider that would initially occupy the 100-km FCC tunnel that will eventually house the 100 TeV FCC-hh hadron collider. The parameter range for the e⁺/e⁻ collider is large, operating at a cm energy from 90 GeV (Z-pole) to 350 GeV (t-tbar production) with the maximum beam current ranging from 1.5 A to 6 mA for each beam, corresponding to a synchrotron radiation power of 50 MW and a radiative energy loss varying from ~30 MeV/turn to ~7500 MeV/turn. This presents challenges for the rf system due to the varying rf voltage requirements and beam loading conditions. In this paper we present a possible gradual evolution of the FCC-ee complex by step-wise expansion, and possibly reconfiguration, of the superconducting RF system. The performance attainable at each step is discussed, along with the possible advantages and drawbacks

Phage Display Based Cloning of Proteins Interacting with the Cytoplasmic Tail of Membrane Immunoglobulins

The reduced quantity and quality of serum immunoglobulins (sIgs) in mutant mice expressing truncated cytoplasmic tails of IgE and IgG1 indicate an active role for the cytoplasmic domains of mIgG1 and mIgE. We used phage display technology to identify candidate proteins able to interact with the cytoplasmic tail of mIgE. Using a murine cDNA B cell library displayed on the surface of phage as prey and the 28 amino acid long cytoplasmic tail of IgE as bait, we isolated phage encoding the murine hematopoietic progenitor kinase 1 (HPK1). Surface plasmon resonance analysis measurements confirmed affinity of HPK1 to the mIgE cytoplasmic tail and revealed association to other immunoglobulin isotypes as well. Immunoprecipitation experiments, using lysates from two B cell lines expressing nitrophenyl (NP) specific mIgE molecules showed co-precipitation of IgE and HPK1. The interaction of HPK1 with the cytoplasmic domains of membrane immunoglobulins indicate an active role of the tails as part of an isotype specific signal transduction, independent from the Igα/Igβ heterodimers, and may represent a missing link to upstream regulatory elements of HPK1 activation

Recent Progress of Dithering System at SuperKEKB

International audienceRecent progress of the dithering system at SuperKEKB is described. Some details of the system layout are shown. Beam orbit and optics related issues are discussed. Preliminary tests of the some components in the Phase 1 beam commissioning or in the bench are described

Early Commissioning of the Luminosity Dither Feedback for SuperKEKB

International audienceSuperKEKB is an electron-positron collider, which aims to achieve a peak luminosity of 8×10³⁵ cm⁻² s^{−1} using what is known as the "nano-beam" scheme. This paper reports on the commissioning and performance of a luminosity dither feedback. The system, based on one previously used at SLAC for PEP-II, is employed for collision orbit feedback in the horizontal plane. Twelve air-core Helmholtz coils drive the positron beam sinusoidally at a frequency near 80 Hz, forming a closed bump at the interaction point. A lock-in amplifier detects the amplitude and phase of the corresponding frequency component of the luminosity signal. When the beams are aligned for peak luminosity, the magnitude of the luminosity component at the dithering frequency becomes zero. The magnitude grows as the beams are offset, and the phase shifts by 180 degrees when the direction of the necessary correction reverses. The hardware and algorithm were tested during SuperKEKB Phase II run. The electron beam orbit was successfully adjusted to minimize the amplitude of the dither frequency component of the luminosity signal, and the optimal condition was maintained by continuously adjusting the electron beam orbit

Early Commissioning of the Luminosity Dither System for SuperKEKB

International audienceSuperKEKB is an electron-positron double ring collider at KEK which aims at a peak luminosity of 8 x 10³⁵ cm⁻²s⁻¹ by using what is known as the ’nano-beam’ scheme. A luminosity dither system is employed for collision orbit feedback in the horizontal plane. This paper reports a system layout of the dither system and algorithm tests during the SuperKEKB Phase 2 commissioning