Author: Hahn, G.
Paper Title Page
MOP030 Developments of 4GSR BPM Electronics 87
 
  • S.W. Jang, G. Hahn, J.Y. Huang, C. Kim, D. Kim, G. Kim, B.K. Shin, D.C. Shin, D. Song
    PAL, Pohang, Republic of Korea
  • W.J. Song
    POSTECH, Pohang, Republic of Korea
  
  The emit­tance of the 4th-gen­er­a­tion stor­age ring (4GSR) to be con­structed in Cheongju-Ochang, Korea, is ex­pected to be ap­prox­i­mately 100 times smaller than the ex­ist­ing 3rd-gen­er­a­tion stor­age ring. With the de­crease in emit­tance, more pre­cise beam sta­bi­liza­tion is re­quired. To meet this re­quire­ment, the res­o­lu­tion of the beam po­si­tion mon­i­tor (BPM) sys­tem also needs to be fur­ther im­proved. We have con­ducted re­search and de­vel­op­ment on the elec­tron­ics of the BPM sys­tem for the 4GSR stor­age ring. In order to per­form fast orbit feed­back in the 4GSR stor­age ring, we need to ac­quire turn-by-turn beam po­si­tion data, with a de­sired beam po­si­tion res­o­lu­tion of 1 ¿m. Ad­di­tion­ally, pro­to­types of the bunch-by-bunch mon­i­tor­ing sys­tem are being de­vel­oped for the trans­verse feed­back sys­tem and lon­gi­tu­di­nal feed­back sys­tem. The in­ter­nally de­vel­oped elec­tron­ics are in­tended to be mod­i­fied for fu­ture use as mon­i­tors for multi-bunch beam en­ergy mea­sure­ments at the end of the lin­ear ac­cel­er­a­tor, by ad­just­ing the logic ac­cord­ingly. In this pre­sen­ta­tion, we will de­scribe more de­tails of the cur­rent sta­tus of the de­vel­op­ment of the beam po­si­tion mon­i­tor elec­tron­ics for the 4GSR in Korea.  
poster icon Poster MOP030 [24.607 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP030  
About • Received ※ 05 September 2023 — Revised ※ 11 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 19 September 2023
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WE1I01
 Online Bunch Length Monitoring for Storage Ring using a Fast Photodiode  
 
  • G. Hahn, C. Kim, D. Kim
    PAL, Pohang, Republic of Korea
  • J.-G. Hwang
    HZB, Berlin, Germany
  • W.J. Song
    POSTECH, Pohang, Republic of Korea
  
  Pro­vid­ing bunch lengths and a fill­ing pat­tern of the bunch train in real-time is one of the im­por­tant chal­lenges in beam in­stru­men­ta­tion of the 3rd gen­er­a­tion light source. In par­tic­u­lar, the time length and in­ten­sity in­for­ma­tion of the syn­chro­tron light is use­ful to beam­lines and their users who per­form time-re­solved ex­per­i­ments. We de­vel­oped an on­line mon­i­tor­ing sys­tem that can mea­sure bunch lengths and a fill­ing pat­tern si­mul­ta­ne­ously by di­rectly ob­serv­ing the syn­chro­tron ra­di­a­tion with a pi­cosec­ond-res­o­lu­tion pho­to­di­ode and high in­put-ana­log-band­width dig­i­tizer. A Gauss­ian de­con­vo­lu­tion method to re­store the orig­i­nal wave­form of syn­chro­tron ra­di­a­tion using the sys­tem im­pulse re­sponse func­tion was de­vel­oped and adopted. In this paper, we pre­sent the ex­per­i­men­tal setup, sig­nal pro­cess­ing method, and sev­eral ma­chine study re­sults in de­tail using the fast pho­to­di­ode in the PLS-II  
slides icon Slides WE1I01 [3.975 MB]  
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WE3C02 Development of a Precise 4d Emittance Meter Using Differential Slit Image Processing 318
 
  • B.K. Shin, G. Hahn
    PAL, Pohang, Republic of Korea
  • M. Chung, C.K. Sung
    UNIST, Ulsan, Republic of Korea
  
  We have de­vel­oped a highly pre­cise 4D emit­tance meter for X-Y cou­pled beams with 4D phase-space (x-x’, y-y’, x-y’, y-x’) which uti­lizes an L-shaped slit and em­ploys novel analy­sis tech­niques. Our ap­proach in­volves two types of slit-screen image pro­cess­ing to gen­er­ate pep­per-pot-like im­ages with great ac­cu­racy. One which we call the "dif­fer­en­tial slit" method, was de­vel­oped by our group. This ap­proach in­volves com­bin­ing two slit-screen im­ages, one at po­si­tion x and the other at po­si­tion x + the size of the slit, to cre­ate a dif­fer­en­tial slit image. The other method we use is the "vir­tual pep­per-pot (VPP)" method, which com­bines x-slit and y-slit im­ages to pro­duce a hole (x,y) image. By com­bin­ing that hole im­ages, we are able to take extra x-y’ and y-x’ phase-space. The "dif­fer­en­tial slit" method is cru­cial for ac­cu­rately mea­sur­ing emit­tance. Through sim­u­la­tions with 0.1 mm slit width using Geant4, the emit­tance un­cer­tain­ties for a 5 nm rad and 0.2 mm size elec­tron beam were 5% and 250% with and with­out the "dif­fer­en­tial slit", re­spec­tively. In this pre­sen­ta­tion, we pro­vide a de­scrip­tion of the method­ol­ogy, the de­sign of slit, and the re­sults of the 4D emit­tance mea­sure­ments.  
slides icon Slides WE3C02 [4.459 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WE3C02  
About • Received ※ 30 August 2023 — Revised ※ 13 September 2023 — Accepted ※ 26 September 2023 — Issue date ※ 28 September 2023
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