M. Statera

The OLYMPUS experiment

OLYMPUS is an experiment mounted by an international collaboration at DESY, Hamburg, Germany to provide a ±1% measurement of the cross section ratio of positron-proton to electron-proton elastic scattering in the range 0.6 < Q2 < 2.2 (GeV/c)2. The goal is to provide a definitive experimental verification of the generally accepted explanation of the discrepancy between cross-section and recoil polarization techniques in determination of the form factor ratio GEp(Q2)/GMp(Q2).

The HERMES recoil detector

The HERMES recoil detector is an exciting addition to the HERMES spectrometer, specifically designed to make one of the first exclusive measurements of deeply virtual Compton scattering (DVCS). DVCS is the experimentally cleanest way to access generalised parton distributions - a theoretical framework that describes the structure of the nucleon. The recoil detector utilises a silicon detector with a large dynamic range capable of reconstructing the momenta of protons in the range of 135 MeV/c to 450 MeV/c, placed directly into the HERA beam vacuum (around the HERMES target) to make both position and energy deposition measurements (for the purposes of momentum reconstruction) of the recoil protons from the process. In addition there is a scintillating fibre tracking (SET) detector placed directly outside the beam vacuum that provides both tracking information and momentum reconstruction data for protons at higher momenta. The third sub-detector is a photon detector that lies concentrically outside the SET and provides useful information on other processes for the purposes of background subtraction. Leptons involved in the interaction will be detected in the existing parts of the HERMES spectrometer. The recoil detectors silicon sub-detector was the subject of a presentation at the IEEE NSS in 2003 by Mathias Reinecke. This presentation is intended as an update on the successful development of the silicon sub-detector as well as providing more information on the impending installation of the detector into the HERMES spectrometer in November 2005

The OLYMPUS Internal Hydrogen Target

Abstract An internal hydrogen target system was developed for the OLYMPUS experiment at DESY, in Hamburg, Germany. The target consisted of a long, thin-walled, tubular cell within an aluminum scattering chamber. Hydrogen entered at the center of the cell and exited through the ends, where it was removed from the beamline by a multistage pumping system. A cryogenic coldhead cooled the target cell to counteract heating from the beam and increase the density of hydrogen in the target. A fixed collimator protected the cell from synchrotron radiation and the beam halo. A series of wakefield suppressors reduced heating from beam wakefields. The target system was installed within the DORIS storage ring and was successfully operated during the course of the OLYMPUS experiment in 2012. Information on the design, fabrication, and performance of the target system is reported.

A high intensity Superconducting atomic beam source

A high intensity atomic beam source design, based on superconducting technology, is presented. The design requires compact sextupole magnets with a tapered bore and pole tip fields of 6-9 T, using superfluid helium if necessary. The cryostat housing these magnets, in addition to maintaining a stable magnet temperature with a minimal thickness along the inner bore, must also function as a cryopump for the atoms that are not focused.

The EuCARD2 Future Magnets Program for Particle Accelerator High-Field Dipoles: Review of Results and Next Steps

The EuCARD2 collaboration aims at the development of a 10 kA-class superconducting, high current density cable suitable for accelerator magnets, to be tested in small coils and magnets capable to deliver 3-5 T when energized in stand-alone mode, and 15-18 T when inserted in a 12-13 T background magnet. REBCO tape, assembled in a Roebel cable, was selected as conductor. The developed REBCO tape has reached a record engineering critical current density, at 4.2 K and 18 T of

A Test Bench for Small Multipolar Magnets for a High-Intensity Superconducting Atomic Beam Source

{\text{956 A/mm}}^{2}

Gamma beam characterization system for ELI-NP: The gamma absorption calorimeter

. Roebel cable carried up to 13 kA at 20 K when tested in a small coil (FeatherM0.4). Then a first dipole magnet, wound with two low-grade Roebel cables of 25 m each, was assembled and tested. The dipole reached the short sample critical current of 6 kA generating more than 3 T central field at about 5.7 K, with indications of good current transfer among cable strands and of relatively soft transition. The construction of a costheta dipole is also discussed. Eucard2 is reaching its objective and is continuing with the H2020-ARIES program aiming at doubling the Je at 20 T to obtain 6 T as standalone and 18 T as insert in a high field facility.

Test Bench Studies and Simulations of Atomic Beam Sources

The R&D activities performed in Ferrara regarding a test bench for low temperature field measurement are presented. The system will be built and tested in Ferrara

Hard Two-Photon Contribution to Elastic Lepton-Proton Scattering Determined by the OLYMPUS Experiment

The ELI-NP Gamma Beam System will deliver an intense gamma beam, in an energy range from 1 to 20 MeV, with unprecedented specifications in terms of brilliance, photon flux and energy bandwidth. A characterization system providing a measurement of the energy spectrum, intensity, space and time profile of the beam is essential for the commissioning and the development of the source, as well as to demonstrate the performance achieved. The technical specifications of the gamma beam prevents to use any traditional gamma spectroscopic detector. A specific system equipped with four basic elements is under development: a sampling calorimeter, for a fast combined measurement of the beam average energy and intensity; a Compton spectrometer, for photon energy spectrum measuring and monitoring; a nuclear resonant scattering spectrometer, for an absolute beam energy calibration and a beam profile imager to be used for alignment and diagnostics purposes. An overview of the ELI-NP gamma characterization system will be given in this work, with a focus on the calorimeter working principle, its expected performances and some preliminary prototype tests.

EuroGammaS gamma characterisation system for ELI-NP-GBS: The nuclear resonance scattering technique

Two new test bench studies have deepened the understanding of polarized gas targets and the atomic beam sources (ABS) that fill them. The attenuation coefficient for beam loss due to rest gas scattering has been measured over a range of beam velocities. The total scattering cross sections can be extracted from these measurements for the first time.Low conductance injection tubes have the potential to increase the thickness of storage cell targets. Injection tubes with internal fins were characterized, and the beam loss at the tube exit was larger than expected. Beam simulations agree with the measured intensity loss only when the atoms’ trajectories have a non‐zero azimuthal velocity component.