Author: Calaga, R.
Paper Title Page
MOPS068 Localization of Transverse Impedance Sources in the SPS using HEADTAIL Macroparticle Simulations 757
 
  • N. Biancacci, G. Arduini, E. Métral, D. Quatraro, G. Rumolo, B. Salvant, R. Tomás
    CERN, Geneva, Switzerland
  • N. Biancacci, M. Migliorati, L. Palumbo
    Rome University La Sapienza, Roma, Italy
  • R. Calaga
    BNL, Upton, Long Island, New York, USA
  
  In par­ti­cle ac­cel­er­a­tors, beam cou­pling impedance is one of the main con­trib­u­tors to in­sta­bil­i­ty phe­nom­e­na that lead to par­ti­cle loss­es and beam qual­i­ty de­te­ri­o­ra­tion. For this rea­son these ma­chines are con­tin­u­ous­ly mon­i­tored and the glob­al and local amount of impedance needs to be eval­u­at­ed. In this work we pre­sent our stud­ies on the local trans­verse impedance de­tec­tion al­go­rithm. The main as­sump­tions be­hind the al­go­rithm are de­scribed in order to un­der­stand lim­its in re­con­struct­ing the impedance lo­ca­tion. The phase ad­vance re­sponse ma­trix is an­a­lyzed in par­tic­u­lar for the SPS lat­tice, study­ing the dif­fer­ent re­sponse from 90,180,270 de­grees phase ad­vance sec­tions. The thin lens­es scheme is also im­ple­ment­ed and new an­a­lyt­i­cal for­mu­las for phase ad­vance beat­ing were de­rived. This avails us to put re­con­struct­ing lens­es ev­ery­where in the lat­tice, and to study their po­si­tion­ing scheme. Lim­its in lin­ear re­sponse are an­a­lyzed. This sets the upper and lower lim­its in re­con­struc­tion to the phase ad­vance mea­sure­ment ac­cu­ra­cy and the lin­ear re­sponse regime limit.  
 
TUPZ009 LHC Machine Protection against Very Fast Crab Cavity Failures 1816
 
  • T. Baer, R. Tomás, J. Tückmantel, J. Wenninger, F. Zimmermann
    CERN, Geneva, Switzerland
  • T. Baer
    Uni HH, Hamburg, Germany
  • R. Calaga
    BNL, Upton, Long Island, New York, USA
  
  For the high-lu­mi­nos­i­ty LHC up­grade pro­gram (HL-LHC), the in­stal­la­tion of crab cav­i­ties (CCs) is es­sen­tial to com­pen­sate the ge­o­met­ric lu­mi­nos­i­ty loss due to the cross­ing angle. The base­line is a local scheme with CCs around the ATLAS and CMS ex­per­i­ments. In a fail­ure case (e.g. a CC quench), the volt­age and/or phase of a CC can change sig­nif­i­cant­ly with a fast time con­stant of the order of a LHC turn. This can lead to large, glob­al be­ta­tron os­cil­la­tions of the beam. Against the back­ground of ma­chine pro­tec­tion, the in­flu­ence of a CC fail­ure on the beam dy­nam­ics is dis­cussed. The re­sults from ded­i­cat­ed track­ing stud­ies, in­clud­ing the LHC up­grade op­tics, are pre­sent­ed. Nec­es­sary coun­ter­mea­sures to limit the im­pact of CC fail­ures to an ac­cept­able level are pro­posed.  
 
TUPZ025 Experience with Offset Collisions in the LHC 1858
 
  • G. Papotti, R. Alemany-Fernandez, F. Follin, R. Giachino, W. Herr, T. Pieloni, M. Schaumann
    CERN, Geneva, Switzerland
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  
  To keep the lu­mi­nos­i­ty under con­trol, some ex­per­i­ments re­quire the ad­just­ment of the lu­mi­nos­i­ty dur­ing a fill, so-called lu­mi­nos­i­ty lev­el­ing. One op­tion is the sep­a­rate the beams trans­verse­ly and ad­just the sep­a­ra­tion to the de­sired col­li­sion rate. The re­sults from con­trolled ex­per­i­ments are re­port­ed and in­ter­pret­ed. The fea­si­bil­i­ty of this method for ul­ti­mate lu­mi­nosi­ties is dis­cussed.  
 
TUPZ026 Alternative Working Point(s) at Injection for the LHC 1861
 
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • R. Tomás
    CERN, Geneva, Switzerland
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  
  Funding: This work partially supported by the US Department of Energy through the LHC Accelerator Research Program (LARP).
At pre­sent, the LHC op­er­ates with a dif­fer­ent frac­tion­al tunes at in­jec­tion and at col­li­sion en­er­gy due to im­proved dy­nam­ic aper­ture in­di­cat­ed by track­ing stud­ies. There­fore, a tune swing cross­ing the 10th order res­o­nance is need­ed dur­ing the be­ta-squeeze. A new pro­pos­al to alter the work­ing point to col­li­sion tunes al­ready at in­jec­tion and dur­ing an en­er­gy ramp is fore­seen to avoid the tune jump. Sim­u­la­tions and mea­sure­ments of the op­tics along with the beam emit­tances and life­time are com­pared to the nom­i­nal in­jec­tion tunes. Fea­si­bil­i­ty for a work­ing point close to the 1/2 in­te­ger is also at­tempt­ed. 		 
 
TUPZ027 Beta* Measurement in the LHC Based on K-modulation 1864
 
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • R. Tomás
    CERN, Geneva, Switzerland
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  
  Funding: This work partially supported by the US Department of Energy through the LHC Accelerator Research Program (LARP).
Ac­cu­rate knowl­edge of the col­li­sion point op­tics is cru­cial to equal­ize the lu­mi­nosi­ties at the dif­fer­ent ex­per­i­ments. K-mod­u­la­tion was suc­cess­ful­ly ap­plied at sev­er­al ac­cel­er­a­tors for mea­sur­ing the lat­tice beta func­tions. In the LHC, it was pro­posed as an al­ter­na­tive method to com­pute the beta* at the col­li­sion points. Re­sults of beta* mea­sure­ments in the LHC based on the K-mod­u­la­tion tech­nique are pre­sent­ed with com­par­isons to nom­i­nal seg­ment-by-seg­ment method. 		 
 
TUPZ029 Observation of Coherent Beam-beam Effects in the LHC 1870
 
  • X. Buffat
    EPFL, Lausanne, Switzerland
  • R. Calaga, S.M. White
    BNL, Upton, Long Island, New York, USA
  • R. Giachino, W. Herr, G. Papotti, T. Pieloni
    CERN, Geneva, Switzerland
  
  Early col­li­sions in the LHC with a very lim­it­ed num­ber of bunch­es with high in­ten­si­ties in­di­cat­ed the pres­ence of co­her­ent beam-beam driv­en os­cil­la­tions. Here we dis­cuss the ex­per­i­men­tal re­sults and com­pare with the ex­pec­ta­tions.  
 
TUPZ034 Impact of Arc Phase Advance on Chromatic Optics in RHIC 1885
 
  • R. Calaga, R. Miyamoto, G. Robert-Demolaize, S.M. White
    BNL, Upton, Long Island, New York, USA
  • R. De Maria, R. Tomás
    CERN, Geneva, Switzerland
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  
  Funding: This work is partially supported by the US Department of Energy through the LHC Accelerator Research program (LARP).
The phase ad­vance be­tween the two in­ter­ac­tion points in RHIC is op­ti­mized for dy­nam­ic aper­ture for a ini­tial de­sign be­ta-star. This may not hold true as RHIC present­ly op­er­ates with a con­sid­er­ably re­duced be­ta-star. Ad­di­tion­al­ly the re­duc­tion of the avail­able beam aper­ture due to an en­larged chro­mat­ic be­ta-beat­ing is ev­i­dent. Re­sults from phase ad­vance scans be­tween the two IPs to re­duce the chro­mat­ic be­ta-beat­ing in model and mea­sure­ments are pre­sent­ed. Im­pact on the sin­gle beam life­time and mo­men­tum aper­ture is com­pared to the nom­i­nal op­tics. 		 
 
WEODA01 Observations of Beam-beam Effects at High Intensities in the LHC 1936
 
  • W. Herr, R. Alemany-Fernandez, R. Giachino, G. Papotti, T. Pieloni
    CERN, Geneva, Switzerland
  • R. Calaga
    BNL, Upton, Long Island, New York, USA
  • E. Laface
    ESS, Lund, Sweden
  • M. Schaumann
    RWTH, Aachen, Germany
  
  First ob­ser­va­tions with col­lid­ing beams in the LHC with bunch in­ten­si­ties close to nom­i­nal and above are re­port­ed. In 2010 the LHC ini­tial­ly op­er­at­ed with few bunch­es spaced around the cir­cum­fer­ence. Beam-beam tune shifts ex­ceed­ing sig­nif­i­cant­ly the de­sign value have been ob­served. In a later stage cross­ing an­gles were in­tro­duced around the ex­per­i­ments to allow the col­li­sions of bunch trains. We re­port the first ex­pe­ri­ence with head-on as well as long range in­ter­ac­tions of high in­ten­si­ty bunch­es and dis­cuss the pos­si­ble per­for­mance reach.  
slides icon Slides WEODA01 [0.409 MB]  
 
WEPC004 Comparison of the Action and Phase Analysis on LHC Orbits with Other Techniques 2004
 
  • J.F. Cardona
    UNAL, Bogota D.C, Colombia
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • R. Tomás
    CERN, Geneva, Switzerland
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  
  Funding: DIB-Universidad Nacional de Colombia
Re­cent­ly ac­quired turn-by-turn data of the LHC is an­a­lyzed using the ac­tion and phase jump tech­nique. The re­sults of this anal­y­sis show a vis­i­ble vari­a­tion of the ac­tion and phase plots at the in­ter­ac­tion re­gions from which optic error es­ti­ma­tions can be done. In this paper error es­ti­ma­tions will be pre­sent­ed and com­par­isons with other ex­ist­ing tech­niques in the LHC, such as the re­cent­ly im­ple­ment­ed Seg­ment-by-seg­ment tech­nique, will be dis­cussed. 		 
 
WEPC028 Record Low Beta-beat of 10% in the LHC 2061
 
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  • M. Aiba
    PSI, Villigen, Switzerland
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • R. Tomás
    CERN, Geneva, Switzerland
  
  Dur­ing the 2011 LHC run sev­er­al mea­sure­ments and cor­rec­tion cam­paigns were con­duct­ed. As a re­sult a peak be­ta-beat of 10% level was achieved. This level, well below the spec­i­fied tol­er­ances of the LHC, im­proves the aper­ture mar­gins and helps min­i­mize the lu­mi­nos­i­ty im­bal­ance be­tween the dif­fer­ent ex­per­i­ments. A com­bi­na­tion of local cor­rec­tions at the in­ser­tion re­gions and an over­all glob­al cor­rec­tion were used to achieve this record low be­ta-beat. The se­quence of the op­tics cor­rec­tions and sta­bil­i­ty along the 2011 run are re­port­ed.  
 
WEPC029 Accuracy of the LHC Optics Measurement based on AC Dipoles 2064
 
  • R. Miyamoto, R. Calaga
    BNL, Upton, Long Island, New York, USA
  • R. Tomás, G. Vanbavinckhove
    CERN, Geneva, Switzerland
  
  Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
The tight tol­er­ances in the LHC re­quires op­tics mea­sure­ment with very good ac­cu­ra­cy. There­fore, AC dipoles are em­ployed as the pri­ma­ry de­vices to mea­sure the LHC op­tics. The ac­cu­ra­cy of the mea­sure­ment is main­ly de­ter­mined by the length of the co­her­ent sig­nal, sig­nal-to-noise ratio of the mea­sure­ment, and the data pro­cess­ing to ef­fec­tive­ly sup­press the noise. This paper pre­sents nu­mer­i­cal and ex­per­i­men­tal stud­ies of how these fac­tors af­fect the ac­cu­ra­cy of the LHC op­tics mea­sure­ment using the AC dipoles. 		 
 
WEPC030 Measurement of Coupling Resonance Driving Terms in the LHC with AC Dipoles 2067
 
  • R. Miyamoto, R. Calaga
    BNL, Upton, Long Island, New York, USA
  • M. Aiba
    PSI, Villigen, Switzerland
  • R. Tomás, G. Vanbavinckhove
    CERN, Geneva, Switzerland
  
  Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
Trans­verse be­ta­tron cou­pling in the LHC is mea­sured from Fouri­er anal­y­sis of turn-by-turn beam os­cil­la­tions ex­cit­ed by AC dipoles. The use of the AC dipole for op­tics mea­sure­ments in­duces a small sys­tem­at­ic error which can be cor­rect­ed with an ap­pro­pri­ate data in­ter­pre­ta­tion. An al­go­rithm to apply this cor­rec­tion to the mea­sure­ment of the cou­pling res­o­nance driv­ing terms is de­vel­oped for the first time. This paper will re­view this new al­go­rithm and pre­sent re­sults of its ap­pli­ca­tion to the LHC. 		 
 
WEPC032 First Measurements of Higher Order Optics Parameters in the LHC 2073
 
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
  • M. Aiba
    PSI, Villigen, Switzerland
  • R. Bartolini
    Diamond, Oxfordshire, United Kingdom
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • M. Giovannozzi, F. Schmidt, R. Tomás
    CERN, Geneva, Switzerland
  • E.H. Maclean
    JAI, Oxford, United Kingdom
  
  High­er order ef­fects can play an im­por­tant role in the per­for­mance of the LHC. Lack of knowl­edge of these pa­ram­e­ters can in­crease the tune foot­print and com­pro­mise the beam life­time. First mea­sure­ments of these pa­ram­e­ters at in­jec­tion and flat­top have been con­duct­ed. De­tailed sim­u­la­tions are com­pared to the mea­sure­ments to­geth­er with dis­cus­sions on the mea­sure­ment lim­i­ta­tions.  
 
THPZ019 High Luminosity Electron-hadron Collider eRHIC 3726
 
  • V. Ptitsyn, E.C. Aschenauer, J. Beebe-Wang, S.A. Belomestnykh, I. Ben-Zvi, R. Calaga, X. Chang, A.V. Fedotov, H. Hahn, L.R. Hammons, Y. Hao, P. He, A.K. Jain, E.C. Johnson, D. Kayran, J. Kewisch, V. Litvinenko, G.J. Mahler, W. Meng, B. Parker, A.I. Pikin, T. Rao, T. Roser, B. Sheehy, J. Skaritka, R. Than, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, Q. Wu, W. Xu
    BNL, Upton, Long Island, New York, USA
  
  We pre­sent the de­sign of a fu­ture high-en­er­gy high-lu­mi­nos­i­ty elec­tron-hadron col­lid­er at RHIC called eRHIC. We plan adding 20 (30) GeV en­er­gy re­cov­ery linacs to ac­cel­er­ate and to col­lide po­lar­ized and un­po­lar­ized elec­trons with hadrons in RHIC. The cen­ter-of-mass en­er­gy of eRHIC will range from 30 to 200 GeV. The lu­mi­nos­i­ty ex­ceed­ing 1034 cm-2s−1 can be achieved in eRHIC using the low-be­ta in­ter­ac­tion re­gion which a 10 mrad crab cross­ing. A nat­u­ral stag­ing sce­nario of step-by-step in­creas­es of the elec­tron beam en­er­gy by bui­lid­ing-up of eRHIC's SRF linacs. We re­port on the eRHIC de­sign and cost es­ti­mates for it stages. We dis­cuss the progress of eRHC R&D pro­jects from the po­lar­ized elec­tron source to the co­her­ent elec­tron cool­ing.