Infra-red divergences in plane wave backgrounds

We show that the emission of soft photons via nonlinear Compton scattering in a pulsed plane wave (laser field) is in general infra-red divergent. We give examples of both soft and soft-collinear divergences, and we pay particular attention to the case of crossed fields in both classical and quantum theories.Comment: 15 pages, 7 figure

Performance of the FONT3 Fast Analogue Intra-train Beam-based Feedback System at ATF

We report results of beam tests of the FONT3 intra- train position feedback system prototype at the Accelerator Test Facility (ATF) at KEK. The feedback system incorporates a novel beam position monitor (BPM) processor with latency below 5 nanoseconds, and a kicker driver amplifier with similar low latency. The 56 nanosecond-long bunchtrain in the ATF extraction line was used to test the prototype feedback system. The achieved latency of 23ns provides a demonstration of intra-train feedback on very short timescales relevant even for the CLIC Linear Collider design

The Clacton Spear: the last one hundred years

In 1911 an eminent amateur prehistorian pulled the broken end of a pointed wooden shaft from Palaeolithic-age sediments at a seaside town in Essex. This artefact, still the earliest worked wood to be discovered in the world, became known as the Clacton Spear. Over the past 100 years it has variously been interpreted as a projectile weapon, a stave, a digging stick, a snow probe, a lance, a game stake and a prod to ward off rival scavengers. These perspectives have followed academic fashions, as the popular views of early hominins have altered. Since discovery the Clacton spear has also been replicated twice, has undergone physical transformations due to preservation treatments, and has featured in two public exhibitions. Within this article the changing context of the spear, its parallels, and all previous conservation treatments and their impacts are assessed.© 2015 Royal Archaeological Institute. This is an Accepted Manuscript of an article published by Taylor & Francis in The Archaeological Journal on 3rd March 2015, available online: http://www.tandfonline.com/doi.org/10.1080/00665983.2015.1008839.The attached document is the author(’s’) final accepted/submitted version of the journal article. You are advised to consult the publisher’s version if you wish to cite from it

Time evolution of ground motion-dependent depolarisation at linear colliders

Future linear colliders plan to collide polarised beams and the planned physics reach requires knowledge of the state of polarisation as precisely as possible. The polarised beams can undergo depolarisation due to various mechanisms. In order to quantify the uncertainty due to depolarisation, spin tracking simulations in the International Linear Collider (ILC) Beam Delivery System (BDS) and at the Interaction Point (IP) have been performed. Spin tracking in the BDS was achieved using the BMAD subroutine library, and the CAIN program was used to do spin tracking through the beam-beam collision. Assuming initially aligned beamline elements in the BDS, a ground motion model was applied to obtain realistic random misalignments over various time scales. Depolarisation at the level of 0.1% occurs within a day of ground motion at a noisy site. Depolarisation at the IP also exceeds 0.1% for the nominal parameter sets for both the ILC and for the Compact Linear Collider (CLIC). Theoretical work is underway to include radiative corrections in the depolarisation processes and simulation of the depolarisation through the entire collider is envisaged.Comment: 8 pages, 4 figures, PST09 proceedings; Proceedings of the 13th International Workshop on Polarised Sources, Targets and Polarimetry 2009, World Scientific 201

Beryllium-7 analyses in seawater by low background gamma-spectroscopy

Author Posting. © Akadémiai Kiadó, 2008. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Journal of Radioanalytical and Nuclear Chemistry 277 (2008): 253-259, doi:10.1007/s10967-008-0739-y.7Be is a cosmogenic isotope produced in the stratosphere and troposphere. 7Be has a half-life of 53.4 days and decays to 7Li emitting a 477 keV gamma line with a branching ratio of 0.104. It is predominantly washed out of the atmosphere through wet deposition. It is a tool for oceanographers to study air sea interaction and water mass mixing. Beryllium’s largely non-reactive nature in the open ocean makes it an excellent conservative tracer. Its conservative nature and extreme dilution in seawater also makes it difficult to concentrate and analyze. Early experiments at WHOI with Fe(OH)3 cartridges to directly collect 7Be by insitu underwater pumps proved ineffective. Collection efficiencies of the cartridges were too low to be consistently useful. At sea chemistry of whole water samples became the method of choice. The use of stable 9Be as a yield monitor further improved the accuracy of the procedure. The method was optimized at WHOI in 2005 using a seawater line that enters WHOI’s coastal research lab. The procedure was then used on an oceanographic cruise on the R/V Oceanus out of Bermuda in the oligotrophic Sargasso Sea.The authors would like to thank DOE, ONR and NSF for funding of this research

Design of the beam delivery system for the International Linear Collider

online : http://pac07.org/proceedings/PAPERS/WEOCAB01.PDFInternational audienceThe beam delivery system for the linear collider focuses beams to nanometer sizes at its interaction point, collimates the beam halo to provide acceptable background in the detector and has a provision for state-of-the-art beam instrumentation in order to reach the ILCs physics goals. this paper describes the design details and status of the baseline configuration considered for the reference design and also lists alternatives

ATF2 Proposal

ATF2 Group Accelerator Physic