• C.A. Thomas, G. Rehm
  Diamond, Oxfordshire
• S.I. Bajlekov
  University of Oxford, Clarendon Laboratory, Oxford
• R. Bartolini, N. Delerue
  JAI, Oxford

Sin­gle shot emit­tance mea­sure­ment is es­sen­tial to as­sess the per­for­mance of new gen­er­a­tion light sources such as linac based X-ray FELs or laser plas­ma wake­field ac­cel­er­a­tors. To this aim, we have de­vel­oped a sin­gle shot emit­tance mea­sure­ment using at least 3 screens in­sert­ed in the beam at the same time, mea­sur­ing the beam size at dif­fer­ent po­si­tions in a drift space in one shot. We pre­sent here test mea­sure­ments per­formed at Di­a­mond in the trans­fer line from the Boost­er to the Stor­age Ring, using thin OTR and also YAG screens. We also com­pare these mea­sure­ments with re­sults from the more con­ven­tion­al quadrupole scan method and also mea­sure­ments using an OTR screen and an as­sem­bly of two cam­eras imag­ing the beam size and the beam di­ver­gence at a point near the waist of the beam. The va­lid­i­ty and lim­its of the new method are dis­cussed in the paper.

• C.A. Thomas, G. Rehm
  Diamond, Oxfordshire
• I.P.S. Martin
  JAI, Oxford

Elec­tron bunch pro­file and length mea­sure­ment from large band­width syn­chrotron ra­di­a­tion with a streak cam­era can be strong­ly lim­it­ed by the chirp in­tro­duced by the length of ma­te­ri­al pre­sent in the input re­frac­tive op­tics of streak cam­eras. Elim­i­na­tion of the chirp can be done ei­ther by fil­ter­ing the band­width of the syn­chrotron ra­di­a­tion puls­es, by mea­sur­ing time re­solved spec­tra with the streak cam­era, or by re­plac­ing the front op­tics lens­es by fo­cussing mir­rors. The first so­lu­tion re­duces the power avail­able, thus lim­it­ing mea­sure­ments to min­i­mum bunch cur­rent that can be too high to as­sess the 'zero' cur­rent bunch length. The sec­ond el­e­gant so­lu­tion al­lows mea­sure­ment of the bunch length with the whole band­width and avail­able power but with loss of the sec­ond sweep axis in the cam­era, so that no beam dy­nam­ics can be ob­served. In order to pre­vent any pulse chirp, keep all the avail­able power and ca­pa­bil­i­ty of beam dy­nam­ics ob­ser­va­tion, we de­signed a new input op­tics ex­clu­sive­ly with mir­rors. We pre­sent here our de­sign and the re­sults of the sys­tem with our streak cam­era, mea­sur­ing 2ps bunch in the new Di­a­mond low-al­pha lat­tice.

• C. Bloomer, G. Rehm, C.A. Thomas
  Diamond, Oxfordshire

We pre­sent our ob­ser­va­tions of the medi­um term and long term sta­bil­i­ty of the pho­ton beams at Di­a­mond Light Source. Drift of the Elec­tron Beam Po­si­tion Mon­i­tors re­sults in real X-ray beam move­ments, ob­served by both Front End X-ray Beam Po­si­tion Mon­i­tors and beam­line scin­til­la­tor screens on some beam­lines. We dis­cuss how we are using these di­ag­nos­tics tools to mea­sure and char­ac­terise the drift. Medi­um term move­ments re­lat­ed to top-up cy­cles are seen, be­lieved to be caused by changes to sin­gle bunch charge, and the long term drift of the elec­tron beam po­si­tion over sev­er­al days and weeks is ex­am­ined. A slow feed­back sys­tem using X-ray Beam Po­si­tion Mon­i­tors has been shown to suc­cess­ful­ly cor­rect this drift. The re­sults of these tri­als are pre­sent­ed.

• I.P.S. Martin, G. Rehm, J. Rowland, C.A. Thomas
  Diamond, Oxfordshire
• R. Bartolini, I.P.S. Martin
  JAI, Oxford

The Di­a­mond stor­age ring has been op­er­at­ed in low alpha mode pro­vid­ing short-pulse ra­di­a­tion for pump-probe ex­per­i­ments and co­her­ent ra­di­a­tion for THz/IR mea­sure­ments. Two lat­tices have been im­ple­ment­ed, with both ca­pa­ble of pro­vid­ing a vari­able alpha in the range ±2x10^-5, down to min­i­mum val­ues well below 1x10^-6. The sec­ond lat­tice ad­di­tion­al­ly pro­vides a low emit­tance of 4nm.​rad, com­pared to 35nm.​rad for the first lat­tice. An overview of op­er­a­tion in low alpha mode is given, along with first mea­sure­ments of co­her­ent emis­sion at long wave­lengths under a va­ri­ety of con­di­tions.

• R. Bartolini, G. Rehm, J. Rowland
  Diamond, Oxfordshire
• P. Kuske
  Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin
• I.P.S. Martin
  JAI, Oxford
• F. Schmidt
  CERN, Geneva

The cor­rect im­ple­men­ta­tion of the non­lin­ear ring model is cru­cial to achieve the top per­for­mance of a syn­chrotron light source. Sev­er­al dy­nam­ics quan­ti­ties can be used to com­pare the real ma­chine with the model and even­tu­al­ly to cor­rect the ac­cel­er­a­tor. Most of these meth­ods are based on the anal­y­sis of turn-by-turn data of ex­cit­ed be­ta­tron os­cil­la­tions. We pre­sent the ex­per­i­men­tal re­sults of the cam­paign of mea­sure­ments car­ried out at the Di­a­mond. A com­bi­na­tion of Fre­quen­cy Map Anal­y­sis and res­o­nant driv­ing terms mea­sure­ments has al­lowed a pre­cise cal­i­bra­tion of the non­lin­ear model ca­pa­ble of re­pro­duc­ing and then cor­rect­ing the non­lin­ear beam dy­nam­ics in the stor­age ring.