Author: Pietralla, N.
Paper Title Page
MOPC151 Design and Commissioning of a Multi-frequency Digital Low Level RF Control System* 433
 
  • M. Konrad, U. Bonnes, C. Burandt, J. Conrad, R. Eichhorn, J. Enders, P.N. Nonn, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  
  Funding: Work supported by DFG through CRC 634 and by the BMBF under 06 DA 9024 I.
Trig­gered by the need to con­trol the su­per­con­duct­ing cav­i­ties of the S-DALINAC, which have a high load­ed qual­i­ty fac­tor and are thus very sus­cep­ti­ble to mi­cro­phon­ics, the de­vel­op­ment of a dig­i­tal low level RF con­trol sys­tem was start­ed. The cho­sen de­sign proved to be very flex­i­ble since other fre­quen­cies than the orig­i­nal 3 GHz may be adapt­ed eas­i­ly: The sys­tem con­verts the RF sig­nal com­ing from the cav­i­ty (e. g. 3 GHz) down to the base band using a hard­ware I/Q de­mod­u­la­tor. The base band sig­nals are dig­i­tized by ADCs and fed into a FPGA where the con­trol al­go­rithm is im­ple­ment­ed. The re­sult­ing sig­nals are I/Q mod­u­lat­ed be­fore they are sent back to the cav­i­ty. The su­per­con­duct­ing cav­i­ties are op­er­at­ed with a self-ex­cit­ed loop al­go­rithm where­as a gen­er­a­tor-driv­en al­go­rithm is used for the low Q nor­mal-con­duct­ing bunch­ing cav­i­ties. A 6 GHz RF front end al­lows the syn­chronous op­er­a­tion of a new 2f bunch­er at the S-DALINAC. Mean­while, a 325 MHz ver­sion has been built to con­trol a pulsed pro­to­type test stand for the p-LINAC at FAIR. We will pre­sent the ar­chi­tec­ture of the RF con­trol sys­tem as well as re­sults ob­tained dur­ing op­er­a­tion. 		 
 
TUPC078 The Impact of the Duty Cycle on Gamma-particle Coincidence Measurements 1183
 
  • P.R. John, J. Leske, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  
  Funding: Supported by BMBF under 06DA9041I
Ra­dioac­tive ion beam fa­cil­i­ties de­liv­er a great va­ri­ety of dif­fer­ent nu­clei and thus open new pos­si­bil­i­ties for gam­ma-ray spec­troscopy with ra­dioac­tive iso­topes. One of the chal­lenges for the ex­per­i­men­tal­ist is the high gamma back­ground. To ob­tain near­ly back­ground-free spec­tra a gam­ma-par­ti­cle co­in­ci­dence mea­sure­ment in in­verse kine­mat­ics is well suit­ed. Also for sta­ble beams this method of­fers a lot of ad­van­tages. A cru­cial point for ex­per­i­men­tal­ists for such kind of ex­per­i­ments is the duty cycle and the beam struc­ture of the ac­cel­er­a­tor. For a typ­i­cal set-up, the ef­fect of the duty cycle and beam struc­ture, e.g. re­sult­ing from dif­fer­ent ion-sources, on data ac­qui­si­tion and thus the ex­per­i­ment will be shown from the ex­per­i­men­tal­ist's point of view. The re­sults will be dis­cussed for se­lect­ed ac­cel­er­a­tors, i.e. UNI­LAC (GSI, Ger­many), REX-ISOL­DE (CERN, Switzer­land) and ATLAS (ANL, USA). 		 
 
WEPC006 Upgrade Plans on the Superconducting Electron Accelerator S-DALINAC 2010
 
  • M. Kleinmann, R. Eichhorn, F. Hug, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  
  Funding: Work supported by DFG through SFB 634
The S-DALINAC is a su­per­con­duct­ing re­cir­cu­lat­ing elec­tron ac­cel­er­a­tor with max­i­mum de­sign en­er­gy of 130 MeV op­er­at­ing in cw at 3 GHz. Even so the gra­di­ents of the su­per­con­duct­ing cav­i­ties are well above de­sign, their de­sign qual­i­ty fac­tor of 3*109 have not been reached so far, lead­ing to high­er heat trans­fer into the liq­uid he­li­um than ex­pect­ed. Due to the lim­it­ed cool­ing power of the cryo-plant being 120 W, the final en­er­gy achiev­able in cw op­er­a­tion is around 85 MeV, cur­rent­ly. In order to pro­vide a cw beam with the de­signed final en­er­gy in the fu­ture, the in­stal­la­tion of an ad­di­tion­al re­cir­cu­la­tion path is pro­ject­ed. We will re­port on the beam-line and the mag­net de­sign for the new re­cir­cu­la­tion path. In ad­di­tion, we will pre­sent the lay­out of two pro­posed scrap­er-sys­tems which will be used to re­move the halo of the elec­tron beam al­low­ing high pre­ci­sion co­in­ci­dence ex­per­i­ments with very low back­ground for nu­cle­ar physics in the fu­ture. 		 
 
WEPC092 Moment-Based Simulation of the S-DALINAC Recirculations* 2223
 
  • S. Franke, W. Ackermann, T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
  • R. Eichhorn, F. Hug, C. Klose, N. Pietralla, M. Platz
    TU Darmstadt, Darmstadt, Germany
  
  Funding: Work supported by DFG under contract SFB 634.
The Su­per­con­duct­ing Lin­ear Ac­cel­er­a­tor S-DALINAC in­stalled at the in­sti­tute of nu­cle­ar physics (IKP) at TU Darm­stadt is de­signed as a re-cir­cu­lat­ing lin­ear ac­cel­er­a­tor. The length of the beam line and the nu­mer­ous ac­cel­er­at­ing struc­tures as well as dipole and quadrupole mag­nets re­quire a high­ly ef­fi­cient nu­mer­i­cal sim­u­la­tion tool in order to as­sist the op­er­a­tors by pro­vid­ing a de­tailed and al­most in­stan­ta­neous in­sight into the ac­tu­al ma­chine sta­tus. A suit­able ap­proach which en­ables a fast on­line cal­cu­la­tion of the beam dy­nam­ics is given by the so-called mo­ment ap­proach where the par­ti­cle dis­tri­bu­tion is rep­re­sent­ed by means of a dis­crete set of mo­ments or by mul­ti­ple dis­crete sets of mo­ments in a mul­ti-en­sem­ble en­vi­ron­ment. Fol­low­ing this ap­proach the V-Code sim­u­la­tion tool has been im­ple­ment­ed at the Com­pu­ta­tion­al Elec­tro­mag­net­ics Lab­o­ra­to­ry (TEMF) at TU Darm­stadt. In this con­tri­bu­tion an overview of the nu­mer­i­cal model is pre­sent­ed to­geth­er with new V-Code sim­u­la­tion re­sults re­gard­ing the S-DALINAC re­cir­cu­la­tion sec­tions.