• P. Kuske, P.O. Schmid
  Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin
• R. Görgen, J. Kuszynski
  Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Elektronen-Speicherring BESSY II, Berlin

With a 7T wig­gler in op­er­a­tion any at­tempts to de­tect the res­o­nant de­po­lar­iza­tion of the elec­tron spins were un­suc­cess­ful at BESSY II. This was at­tribut­ed to the severe­ly re­duced final de­gree of spin po­lar­iza­tion in the al­ter­nat­ing fields of the strong wig­gler which on the other hand near­ly dou­ble the ra­di­a­tion loss per turn. The key to a clear de­tec­tion of the de­po­lar­iza­tion were the im­prove­ment of the sen­si­tiv­i­ty of the po­larime­ter based on the spin de­pen­dent Tou­schek scat­ter­ing cross sec­tion and the more ef­fec­tive and thus full de­po­lar­iza­tion of the beam. In the paper the steps taken will be pre­sent­ed in de­tail. With these im­prove­ments in place the high pre­ci­sion en­er­gy de­ter­mi­na­tion of the stored beam can be per­formed once again in par­al­lel to the nor­mal user op­er­a­tion and with­out any no­tice­able per­tur­ba­tions to the beam.

• P.O. Schmid, P. Kuske
  Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin
• D.B. Engel, J. Feikes, R. Müller, G. Wüstefeld
  Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Elektronen-Speicherring BESSY II, Berlin

In this paper we pre­sent the re­sults of our stud­ies em­ploy­ing LOCO and MML for op­tics cal­i­bra­tion at the MLS and at the BESSY II stor­age rings. Both the stan­dard user modes and ded­i­cat­ed low alpha modes were anal­ysed.

• R. Müller, B. Franksen, R. Görgen, R. Lange, I. Müller, J. Rahn, T. Schneegans
  Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Elektronen-Speicherring BESSY II, Berlin
• P. Kuske
  Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin

In view of in­creased pro­cess­ing band­width at de­mand­ing ex­per­i­ments and the need for rapid com­pen­sa­tion of noise spikes and new, yet un­known ex­ci­ta­tions a fast orbit feed­back aim­ing at noise sup­pres­sion in the 1Hz-50Hz range has be­come manda­to­ry for the 3rd gen­er­a­tion light source BESSY II. As a first step the fast set­point trans­mis­sion plus the re­place­ment of all cor­rec­tor power sup­plies is fore­seen. Later - in com­bi­na­tion with top-up op­er­a­tion - orbit sta­bil­i­ty can be fur­ther im­proved by re­plac­ing today's mul­ti­plexed ana­log beam po­si­tion mon­i­tors by par­al­lel pro­cess­ing fast dig­i­tal units. This paper de­scribes how the pilot in­stal­la­tion of a small sub­set of fast cor­rec­tor power sup­plies al­ready al­lows to tune per­for­mance and study the ben­e­fits for today's most sen­si­ble ex­per­i­ments.

• 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.