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Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
Presentatie Freya Blekman
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Presentatie Freya Blekman

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Managing the data of the Large Hadron Collider

Managing the data of the Large Hadron Collider

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  • 1. Managing  the  data  of  the   Large  Hadron  Collider     (and  other  particle  physics   experiments)     Prof.  Dr.  Freya  Blekman   Interuniversity  Institute  for  High  Energies   Vrije  Universiteit  Brussel  
  • 2. O H C
  • 3. νe u d e ≈  
  • 4. The  “Standard  Model”   §  Over  the  last  ~100  years:  The  combination  of    Quantum   Field  Theory  and  discovery  of  many  particles  has  led  to     §  The  Standard  Model  of  Particle  Physics   §  With  a  new  “Periodic  Table”  of  fundamental  elements   Matter  particles   Force  particles   One  of  the  greatest   achievements  of  20th   Century  Science      
  • 5. The  Standard  Model!      
  • 6. The  Large  Hadron  Collider   General  Purpose,   pp,  heavy  ions   CMS ATLAS   General  Purpose:   pp,  heavy  ions  
  • 7. Compact  Muon  Solenoid  (CMS)   Silicon Pixels ccc µ+ e+ γ, πo K-, π- ,p,… ν Muon detectors Hadron calorimeter Crystal Electromagnetic calorimeter 4 Tesla Solenoid All Silicon Strip Tracker Ko → π+ π- , …etc
  • 8. Quite  a  camera   §  CMS  is  like  a  camera  with  90  Million  pixels   §  But  no  ordinary  camera   §  It  can  take  up  to  40  million  pictures  per  second   §  The  pictures  are  3  dimensional   §  And  at  15  million  kilograms,  it’s  not  very  portable   §  LHC  data  challenge:  The  problem  is  that  we  cannot   store  all  the  pictures  we  can  take  so  we  have  to   choose  the  good  ones  fast!    
  • 9. Experimental  Challenges  –  Big  Data  in  Particle  Physics   §  Collisions  are  frequent       §  Beams  cross  ~  16.5  million  times  per  second  at   present   §  About  20-­‐30  pairs  of  protons  collide  each   crossing   §  Interesting  collisions  are  rare  -­‐       §  less  than  1  per  10  billion  for  some  of  the  most   interesting  ones   §  We  record  only  about  400   events  per  second.     §  We  must  pick  the  good  ones  and  decide   fast!   §  Decision  (‘trigger’)  levels   §  A  first  analysis  is  done  in  a  few  millionths  of  a   second  and  temporarily  holds  100,000  pictures   of  the  16,500,000   §  A  final  analysis  takes  ~  0.1  second  and  we  use   ~10000  computers     §  We  still  end  up  with  lots  of   data  –  1  GB  per  second!   Symmetry  magazine’s  summary  infographic  of  LHC  data  volumes  
  • 10. CERN  
  • 11. Data  distribution   §  Grid  connects  >100,000  processors  in  34  countries   22  Petabytes  in  2011  
  • 12. CMS  data  in    Belgium   §  In  Flanders:  CMS  T2  hosted  at  VUB   §  Alternative  T2  at  UCL   §  Access  to  all  CMS  members  all  over  the  world   §  And  main  working  node  for  all  Flemish  (+  ULB/UMons)   particle  physicists   §  Brussels  Computing  cluster  (Tier  2  computer  center):      Consist  of  modular  PCs       440  TB  storage  space  (and  growing)  for  Belgian   users     2.2  PB  storage  space  for  CMS      19  TeraFLOPS  (FLoating-­‐point  Operations  Per  Second)      Funding  agencies:  FRS-­‐FNRS  (ULB,  UMons)  FWO-­‐BigScience  –   Vlaams  Supercomputing  Centrum  (VUB)    
  • 13. Other  CMS  data   DBTA Workshop on Big Data, Cloud Data Management and NoSQLBig Data Management at CERN: The CMS Example Other CMS Documents" x    4000  people      …  for  many  decades J.A. Coarasa (CERN) 25!
  • 14. Other  CMS  data   DBTA Workshop on Big Data, Cloud Data Management and NoSQLBig Data Management at CERN: The CMS Example Other CMS Documents: Size" A printed pile of all CMS documents that are already in a managed system = 1.0 x (Empire State building) Plus we have almost the same amount spread all over the place (PCs, afs, dfs, various  websites  …) J.A. Coarasa (CERN) 26!
  • 15. LHC  open  data?  §  LHC  and  CERN  have  very   strict  policies  regarding   publication  of  their  results   §  ALL  journal  publications   (including  those  in  Nature/ Science)  are  made  public   §  Publishing  in  open  access   journals  the  norm   §  However,  most  of  our  data  is   only  accessible  to  those  in  the   collaboration   §  Exception:  there  are  datasets  available  for  education   use   §  http://physicsmasterclasses.org/index.php   Secondary  school  student  accessing  public  CMS   data  at  Vrije  Universiteit  Brussel  
  • 16. Open  data  in  (astro)  particle  physics   §  The  IceCube  experiment  is  another  particle  physics   experiment  studying  elementary  particles  of   astrophysical  origin   §  Based  at  the  South  Pole,   IceCube  includes  Belgian   scientists  from  VUB/ULB/ UGent/Umons   §  IceCube  data  is  analysed   with  the  same  cluster  in   Brussels  as  mentioned   before  
  • 17. Extreme  High  energy  neutrinos   §  One  of  the  most  exciting  IceCube  results  involves   the  observation  of  outrageously  high-­‐energy   neutrinos  from  cosmic  origin   §  Evidence  for  High-­‐Energy  Extraterrestrial  Neutrinos  at  the  IceCube  Detector,   IceCube  Collaboration,  Science  342,  1242856  (2013).  DOI:  10.1126/science. 1242856     §  After  publication,  the  IceCube   collaboration  has  made  this   data  available  to  the  scientific   community   §  http://icecube.wisc.edu/science/ data    
  • 18. §  Working  through  40  million  collisions  per  second   provides  a  daunting  challenge  processing  huge   amounts  of  data   §  Journal  publications  of  LHC  experiments  all  public   §  Other  experiments  such  as  IceCube  also  make  some   of  their  datasets  public  after  publication     Outlook  and  Conclusion  
  • 19. pp physics at the LHC corresponds to conditions around here HI physics at the LHC corresponds to conditions around here
  • 20. Where  the  largest  and  smallest  things  meet  
  • 21. The  Dark  Side   §  We  now  know  that  only  ~5%  of  the  energy  in  the   universe  is  ordinary  matter  (remember  E=mc2).     §  25%  is  dark  matter     §  SUSY  theories  can  happily  predict  this  amount   §  There  are  other  possibilities  but  SUSY  is  a  favorite   §  Provides  great  dark  matter  candidates       (e.g.  Neutralino  or  Gravitino)   §  Leads  to  remarkable  unification  of  field  strengths   §  And  it  fixes  the  Higgs  mass  problem  
  • 22. How  would  we  see  the  Higgs  Boson  ?   Simulation  –  to  predict  and  design  detector  –  and  to  compare  to  what  we  actually  see   NB:  These  old  plots  correspond  to  ~50  times  more  sensitivity  than  we  have  now  (20x  more  data,  2x  the  energy)!  
  • 23. §  all  channels  together:                       comb.  significance:  4.9  σ   §  expected  significance     for  SM  Higgs:  5.9  σ       Characterization  of  excess  near  125  GeV   26
  • 24. [GeV]4lm Events/3GeV 0 2 4 6 8 10 12 [GeV]4lm Events/3GeV 0 2 4 6 8 10 12 Data Z+X *,ZZZ =126 GeVHm µ, 2e2µ7 TeV 4e, 4 µ, 2e2µ8 TeV 4e, 4 CMS Preliminary -1 = 8 TeV, L = 5.26 fbs;-1 = 7 TeV, L = 5.05 fbs [GeV]4lm 80 100 120 140 160 180
  • 25. Standard  Model  Higgs  Decays   §  The  SM  Higgs  is  unstable   §  Decays  “instantly”  in  a  number  of  ways  with  very  well  known  probabilities   (called  Branching  Fractions  or  Ratios  that  sum  up  to  1).   §  Branching  ratios  change  with  mass  as  seen  here   §  Some  decay  modes  are  more  easily  seen  than  others      Firstly  if  they  end  with  electrons,  muons,    or  photons  
  • 26. Supersymmetry  
  • 27. What  made  us  so  sure  about  the  Higgs?   §  The  Brout-­‐Englert-­‐Higgs  theory  has  predictable   consequences   §  It  predicts  very  heavy  force  particles  that  carry  the  weak   nuclear  force  known  as  the  W+,  W-­‐  and  Zo     §  The  W+,  W-­‐    should  both  have  a  mass  of  80.4  GeV        Note  that  the  proton  has  a  mass  of  1  GeV  so  these  are  very  heavy   fundamental  particles!   §  The  Zo  should  have  a  mass  of  91.1  GeV     §  We  find  these  predicted  particles  &  measure  their  masses   §  For  instance,  the  Zo  should  decay  to  two  muons.  We  can   measure  their  momenta  and  reconstruct  the  Zo  mass.   §  If  we  do  this  for  many  Zo  particles,  a  distribution  of  the  mass   values  we  get  should  have  a  very  predictable  shape.  

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