Diagnostics
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D.
Alves
,
A.
Curcio
,
R. O.
Jones
,
R.
Kieffer
,
T.
Lefèvre
,
S.
Mazzoni
,
N.
Mounet
,
E.
Senes
,
A.
Schloegelhofer
,
K.
Fedorov
,
P.
Karataev
,
D.
Harryman
,
K.
Lekomtsev
,
V. V.
Bleko
,
S. Y.
Gogolev
,
A. S.
Konkov
,
J. S.
Markova
,
A. P.
Potylitsyn
,
D. A.
Shkitov
,
M.
Billing
,
J.
Conway
,
Y. Padilla
Fuentes
,
J.
Shanks
,
M.
Apollonio
,
L.
Bobb
,
A.
Aryshev
,
J.
Gardelle
,
K.
Lasocha
Open Access
Abstract: Over the past 3 years, the emission of Cherenkov Diffraction Radiation (ChDR), appearing when a relativistic charged particle moves in the vicinity of a dielectric medium, has been investigated as a possible tool for non-invasive beam diagnostics. ChDR has very interesting properties, among which is the emission of a large number of photons in a narrow and well-defined solid angle which provides excellent conditions for signal detection with very little background. This contribution will present a collection of recent beam measurement results performed at several facilities such as the Cornell Electron Storage Ring (CESR), the Ad- vanced Test Facility 2 (ATF2) at KEK and the CLEAR test facility at CERN. These results, complemented by simulations, are showing that both the incoherent and coherent emission of Cherenkov Diffraction radiation could open the path for a new kind of beam diagnostic technique for relativistic charged particle beams.
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Sep 2019
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Diagnostics
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Open Access
Abstract: Resonant Spin Depolarization (RSD) is a well-known technique that has been employed by Diamond Light Source (DLS) for beam energy measurements. In this project, we study a new approach to make RSD compatible with user beam operation and provide a continuously updated online measurement. An array of four custom-made scintillation detectors has been installed around the beam pipe, downstream of collimators to capture the highest fraction of lost particles and maximize the count rate. The excitation is gated to half of the stored bunches and the acquisition system counts losses in both halves independently. Using the count in the un-excited part for normalisation suppresses external factors that modify the loss rate. Different parameters of the measurement, like excitation kick strength and duration have been explored to optimise depolarisation and to increase the reliability of the measurement.
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Jan 2019
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Diagnostics
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R.
Kieffer
,
L.
Bartnik
,
M.
Bergamaschi
,
V. v.
Bleko
,
M.
Billing
,
L.
Bobb
,
J.
Conway
,
M.
Forster
,
P.
Karataev
,
A. s.
Konkov
,
R. o.
Jones
,
T.
Lefevre
,
J. s.
Markova
,
S.
Mazzoni
,
Y.
Padilla Fuentes
,
A. p.
Potylitsyn
,
J.
Shanks
,
S.
Wang
Open Access
Abstract: We report on the observation of incoherent Cherenkov radiation emitted by a 5.3 GeV positron beam circulating in the Cornell electron-positron storage ring as the beam passes in the close vicinity of the surface of a fused silica radiator (i.e., at a distance larger than 0.8 mm). The shape of the radiator was designed in order to send the Cherenkov photons towards the detector, consisting of a compact optical system equipped with an intensified camera. The optical system allows both the measurements of 2D images and angular distribution including polarization study. The corresponding light intensity has been measured as a function of the distance between the beam and the surface of the radiator and has shown a good agreement with theoretical predictions. For highly relativistic particles, a large amount of incoherent radiation is produced in a wide spectral range. A light yield of 0.8×10−3 photon per particle per turn has been measured at a wavelength of 600±10 nm in a 2 cm long radiator and for an impact parameter of 1 mm. This will find applications in accelerators as noninvasive beam diagnostics for both leptons and hadrons.
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Aug 2018
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Diagnostics
Magnets
Mechanical Engineering
Optics
Vacuum
|
R.
Bartolini
,
C.
Abraham
,
M.
Apollonio
,
C. P.
Bailey
,
M. P.
Cox
,
A.
Day
,
R. T.
Fielder
,
N. P.
Hammond
,
M. T.
Heron
,
R.
Holdsworth
,
J.
Kay
,
I. P. S.
Martin
,
S.
Mhaskar
,
A.
Miller
,
T.
Pulampong
,
G.
Rehm
,
E. C. M.
Rial
,
A.
Rose
,
A.
Shahveh
,
B.
Singh
,
A.
Thomson
,
R. P.
Walker
Open Access
Abstract: Diamond has recently successfully commissioned a major change in the lattice consisting of the substitution of a standard double-bend achromat (DBA) cell with a modified four-bend achromat (4BA) cell called “double-double bend achromat” (DDBA). This work stems from the original studies initiated in 2012 towards a Diamond upgrade and provides the benefit of an additional straight section in the ring available for insertion devices. This paper reviews the DDBA design and layout, the implications for technical subsystems, the associated engineering challenges and the main results of the commissioning completed in April 2017.
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May 2018
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Diagnostics
Vacuum
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Open Access
Abstract: In recent years, there has been an increasing demand for noninvasive beam size monitoring on particle accelerators. Ideally, these monitors should be cost effective and require little or no maintenance. These monitors should also be suitable for both linear and circular machines. Here, the experimental setup is described in detail, and the results from a diffraction radiation beam size monitor are presented. This monitor has been tested on the Cornell Electron Storage Ring using a 1 mA (
1.6
×
10
10
particles per bunch) single bunch electron beam at 2.1 GeV energy. Images of the target surface and the angular distribution of the emitted diffraction radiation were acquired at wavelengths of 400 and 600 nm. These measurements are compared to two analytical models.
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Mar 2018
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Diagnostics
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Open Access
Abstract: We describe the development of firmware to support Longitudinal Bunch by Bunch Feedback at Diamond Light source. As well as feedback, the system supports complex experiments and the capture of detailed electron beam diagnostics. In this paper we describe the firmware development and some details of the processing chain. We focus on some of the challenges of FPGA development from the perspective of a software engineer.
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Jan 2018
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I02-Macromolecular Crystallography
Data acquisition
Detectors
Diagnostics
Health Physics
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Abstract: The deubiquitinating enzyme USP7 has a pivotal role in regulating the stability of proteins involved in fundamental cellular processes of normal biology and disease. Despite the importance of USP7, the mechanisms underlying substrate recognition and catalytic activation are poorly understood. Here we present structural, biochemical, and biophysical analyses elucidating the molecular mechanism by which the C-terminal 19 amino acids of USP7 (residues 1084-1102) enhance the ubiquitin cleavage activity of the deubiquitinase (DUB) domain. Our data demonstrate that the C-terminal peptide binds the activation cleft in the catalytic domain and stabilizes the catalytically competent conformation of USP7. Additional structures of longer fragments of USP7, as well as solution studies, provide insight into full-length USP7, the role of the UBL domains, and demonstrate that both substrate recognition and deubiquitinase activity are highly regulated by the catalytic and noncatalytic domains of USP7, afeature that could be essential for the proper function of multi-domain DUBs.
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Aug 2016
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I02-Macromolecular Crystallography
I04-Macromolecular Crystallography
Data acquisition
Detectors
Diagnostics
Health Physics
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Diamond Proposal Number(s):
[6386]
Open Access
Abstract: α-actinin 2 (ACTN2) is the only muscle isoform of α-actinin expressed in cardiac muscle. Mutations in this protein have been implicated in mild to moderate forms of hypertrophic cardiomyopathy (HCM). We have investigated the effects of two mutations identified from HCM patients; A119T and G111V, on the secondary and tertiary structure of a purified actin binding domain of ACTN2 by circular dichroism and X-ray crystallography, and show small but distinct changes for both mutations. We also find that both mutants have reduced F-actin binding affinity, although the differences are not significant. The full length mEos2 tagged protein expressed in adult cardiomyocytes shows that both mutations additionally affect Z-disc localisation and dynamic behaviour. Overall, these two mutations have small effects on structure, function and behaviour, which may contribute to a mild phenotype for this disease.
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Aug 2016
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I02-Macromolecular Crystallography
Detectors
Diagnostics
Health Physics
|
Open Access
Abstract: Replisome assembly at eukaryotic replication forks connects the DNA helicase to DNA polymerases and many other factors. The helicase binds the leading-strand polymerase directly, but is connected to the Pol alpha lagging-strand polymerase by the trimeric adaptor Ctf4. Here, we identify new Ctf4 partners inaddition to Pol alpha and helicase, all of which contain a "Ctf4-interacting-peptide" or CIP-box. Crystallographic analysis classifies CIP-boxes into two related groups that target different sites on Ctf4. Mutations in the CIP-box motifs of the Dna2 nuclease or the rDNA-associated protein Tof2 do not perturb DNA synthesis genome-wide, but instead lead to a dramatic shortening of chromosome 12 that contains the large array of rDNA repeats. Our data reveal unexpected complexity of Ctf4 function, as a hub that connects multiple accessory factors to the replisome. Most strikingly, Ctf4-dependent recruitment of CIP-box proteins couples other processes to DNA synthesis, including rDNA copy-number regulation.
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Aug 2016
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B21-High Throughput SAXS
I02-Macromolecular Crystallography
Data acquisition
Diagnostics
Health Physics
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Diamond Proposal Number(s):
[12346]
Open Access
Abstract: Protein antibiotics (bacteriocins) are a large and diverse family of multidomain toxins that kill specific Gram-negative bacteria during intraspecies competition for resources. Our understanding of the mechanism of import of such potent toxins has increased significantly in recent years especially with the reporting of several structures of bacteriocin domains. Less well understood is the structural biochemistry of intact bacteriocins and how these compare across bacterial species. Here we focus on endonuclease (DNase) bacteriocins that target the genomes of Escherichia coli and Pseudomonas aeruginosa , known as E-type colicins and S-type pyocins, respectively, bound to their specific immunity (Im) proteins. First, we report the 3.2 Å structure of the DNase colicin ColE9 in complex with its ultra-high affinity immunity protein, Im9. In contrast to Im3, which when bound to the ribonuclease (rRNase) domain of the homologous colicin ColE3 makes contact with the translocation (T-) domain of the toxin, we find that Im9 makes no such contact and only interactions with the ColE9 cytotoxic domain are observed. Second, we report small angle X-ray scattering (SAXS) data for two S-type DNase pyocins, S2 and AP41, into which are fitted recently determined X-ray structures for isolated domains. We find that DNase pyocins and colicins are both highly elongated molecules even though the order of their constituent domains differs. We discuss the implications of these architectural similarities and differences in the context of the translocation mechanism of protein antibiotics through the cell envelope of Gram-negative bacteria.
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Jul 2016
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