IHEP Beijing, Beijing
A DC Current Transformer (DCCT) as a standard diagnostic system for beam current plays an important role in BEPCII, the upgrade project of the Beijing Electron Positron Collider. Two DCCTs are operated in the BEPCII storage ring now, separated in electron ring and positron ring, used to monitor the beam current, the beam injection rate and the beam loss rate, meanwhile to help to calculate the beam lifetime. In this paper, the mechanical structure design, readout system and data processing are presented. The progress of DCCTs on each step of BEPCII commissioning, such as improving the beam lifetime，and solution of background noise, are also included.
INFN/LNF, Frascati (Roma)
INFN-Roma, Roma
The DAΦNE Beam Test Facility (BTF), initially optimized to produce single electrons and positrons in the 25-750 MeV energy range, can now provide beam in a wider range of intensity, up to 1010 electrons/pulse. The facility has been also equipped with a system for the production of tagged photons, and the possibility of photo-production of neutron is under study. Different diagnostic tools have been developed and are available for high-energy users and accelerator community to monitor and check beam and device under test performance. The main results obtained, the performance and the most significant characteristics of the facility diagnostics and operation are presented, as well as the users experience collected during these years of operation.
KEK, Ibaraki
Recent high-intensity machines with a multi-bunched beam demand bunch-by-bunch beam diagnostics. Especially in a colliding machine such as KEKB, the beam-beam effect is one of the main issues from the viewpoint of beam dynamics. Recently, KEKB achieved an effective head-on collision by using of crab cavities and gained a higher specific luminosity. A gated beam-position monitor, being capable of measuring the beam phase as well as the transverse position of a specific bunch in a bunch train, has been developed and is used to measure a beam-beam kick at KEKB. The monitor detects the beam position with a resolution of a few micrometers. The monitor demonstrated the effect of the crab cavities and estimated the effective horizontal beam size at the interaction point from a linear part of a beam-beam kick. Moreover, the monitor detected a displacement of the horizontal beam position along a bunch train under the crabbing collision. We estimate that the horizontal displacement is caused by an asymmetric kick of the crab cavities, which is based on a bunch-by-bunch phase modulation due to transient beam loading.
INFN/LNF, Frascati (Roma)
Università degli Studi di Firenze, Firenze
INOA, Firenze
VIGO System S.A., Ozarow Maz.
Low cost bunch-by-bunch longitudinal diagnostics is a key issue of modern accelerators. To face up this challenging demand mid-IR compact uncooled PC HgCdTe detectors have been characterized at DAΦNE. These devices were used to monitor the emission of e- bunches. The first experiment allowed to record 2.7 ns long bunches in the e- ring with a FWHM of a single pulse of about 600 ps. To improve diagnostics at DAΦNE an exit port on a bending magnet of the e+ ring has been set-up to monitor the positron bunch structure. The front-end of this port includes an HV chamber hosting a gold-coated plane mirror that collects and deflects the radiation through a ZnSe window. After the window a simple optical layout in air will focus the radiation on IR detectors. The instrumentation will allow comparison in the ns time domain between the two rings and to identify and characterize bunch instabilities. To improve the established performances new faster IR photovoltaic detectors with sub-ns response times are under characterization. In this work we will present the actual status of the 3+L experiment and new measurements obtained with photovoltaic detectors on the e- ring.
