Beam studies at the SPEAR3 synchrotron using a digital optical mask

The 3GeV SPEAR3 synchrotron light source operates in top-up injection mode with up to 500mA circulating in the storage ring (equivalently 392nC). Each injection pulse contains 40–80pC producing a contrast ratio between total stored charge and injected charge of about 6500:1. In order to study transi...

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Bibliographic Details
Published in:Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2016-05, Vol.817 (C), p.46-56
Main Authors: Zhang, H.D., Fiorito, R.B., Corbett, J., Shkvarunets, A.G., Tian, K., Fisher, A.
Format: Article
Language:English
Subjects:
Beams (radiation)
Charge
Detectors
Devices
Digital micro-mirror-array device
Imaging
Injection
INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
Masking
Masks
Optical mask
Optical synchrotron radiation beam line
Stanford positron electron asymmetric ring
Synchrotron diagnostics
Synchrotrons
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Summary:The 3GeV SPEAR3 synchrotron light source operates in top-up injection mode with up to 500mA circulating in the storage ring (equivalently 392nC). Each injection pulse contains 40–80pC producing a contrast ratio between total stored charge and injected charge of about 6500:1. In order to study transient injected beam dynamics during user operations, it is desirable to optically image the injected pulse in the presence of the bright stored beam. In the present work this is done by imaging the visible component of the synchrotron radiation onto a digital micro-mirror-array device (DMD), which is then used as an optical mask to block out light from the bright central core of the stored beam. The physical masking, together with an asynchronously-gated, ICCD imaging camera, makes it possible to observe the weak injected beam component on a turn-by-turn basis. The DMD optical masking system works similar to a classical solar coronagraph but has some distinct practical advantages: i.e. rapid adaption to changes in the shape of the stored beam, a high extinction ratio for unwanted light and minimum scattering from the primary beam into the secondary optics. In this paper we describe the DMD masking method, features of the high dynamic range point spread function for the SPEAR3 optical beam line and measurements of the injected beam in the presence of the stored beam.
ISSN:0168-9002
1872-9576
DOI:10.1016/j.nima.2016.01.071