ANL, Lemont, Illinois, USA
The Advanced Photon Source (APS) is building a fourth-generation storage ring (4GSR), replacing the present double-bend achromat lattice with a multibend achromat system thereby allowing the production of ultra-bright x-ray beams. The new lattice enables a two-order-of-magnitude reduction in horizontal beam emittance and a factor of two increase in beam current. The result is an electron beam of very high energy- and power-densities. Initial predictions suggest virtually any material struck by the undiluted electron beam will be damaged. Two experimental beam abort studies have been conducted on collimator test pieces in the present APS SR to inform the design of a fully-functional machine protection system for APS 4GSR operations at 200 mA. A comprehensive suite of diagnostics were employed during the studies The diagnostics used in these experiments are not new, but employed in different ways to obtain unique data sets. With these data sets now in hand, we are developing new numerical tools to guide collimator design.
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ANL, Lemont, Illinois, USA
Confirmation of pm rad scale emittances from the Advanced Photon Source Upgrade electron storage ring necessitates direct measurement of the electron beam size. In the present work, we motivate design choices for the X-ray beam size monitor shielding enclosure for the Advanced Photon Source Upgrade. Particular emphasis is given to outlining design choices from the perspectives of safety, overall project construction schedule and eventual beamline operations.
ANL, Lemont, Illinois, USA
To best leverage the orders of magnitude average brightness increase of multi-bend achromat synchrotron radiation storage rings, ambitious beam stability requirements are imposed. One system that will be employed at the Advanced Photon Source Upgrade in support of photon beam stability will be X-ray beam position monitors. In the present work, electrical characterisation of several types of photodiodes are evaluated for potential use in X-ray beam position monitors.
AAI/ANL, Lemont, Illinois, USA
ANL, Lemont, Illinois, USA
The initial observations of optical synchrotron radiation (OSR) emitted over millions of passes from a few electrons circulating in the Particle Accumulator Ring (PAR) at the Advanced Photon Source have been done with a digital CMOS camera and a synchroscan streak camera operating at 117.3 MHz. The discrete changes of integrated counts in the CMOS image region of interest are ascribed to single electron steps at ~3500 cts per electron. Circulations of a single electron at 375 MeV and at 425 MeV were demonstrated in the 12-bit digital FLIR USB3 camera images. The Hamamatsu C5680 streak camera operating at the 12th harmonic of the fundamental revolution frequency at 9.77 MHz was used to measure the zero-current bunch length from 0.5 nC circulating charge down to 10s of electrons or <10 aC. The latter cases were performed with 6-ps temporal resolution for the first time anywhere, to our knowledge. We report a preliminary effective bunch length of 276 ± 36 ps for 57 electrons (9.1 aC) stored based on a fit to a single Gaussian peak. The results will be compared to the standard zero-current model for the ring.
ANL, Lemont, Illinois, USA
Relativistic electron beams in storage rings radiate a significant fraction of beam energy per turn. As demonstrated in previous experiments, with the radiofrequency accelerating structures off, the turn-by-turn time of arrival of the electron bunch can be observed from the synchrotron radiation that it produces using a streak camera. In the present work, we present measurements of the energy loss per turn of an initially short electron bunch (~1 ps RMS) from a photocathode electron gun in the Advanced Photon Source Particle Accumulator Ring (375 MeV, 102 ns revolution period). With the streak camera synchroscan locked to the twelfth harmonic of the revolution frequency (117.3 MHz), we observe an injection transient in the horizontal direction.