now2008 Paola Sala for the CNGS SBWG CNGS status Paola Sala, INFN Milano on behalf of the CNGS Secondary beam working group

now2008 Paola Sala for the CNGS SBWG Cern Neutrino to Gran Sasso Commissinioning: 2006 Operation since 2007 Search for    oscillation in appearance 732 km baseline

now2008 Paola Sala for the CNGS SBWG BN collimator, d=14mm Be window, t=100  m Proton Beam From SPS: 400 GeV/c Cycle length: 6 s Extractions: –2 separated by 50ms Pulse length: 10.5  s Beam intensity: –2x 2.4 · ppp  ~0.5  mm Beam performance: –4.5· pot/year (shared mode) At LNGS OPERA emulsion bricks (1.21 kton) Icarus 600 t LAr TPC

now2008 Paola Sala for the CNGS SBWG 43.4m 100m 1095m18m5m 67m 2.7m TBID Air cooled graphite target magazine –4 in situ spares –2.7 interaction lengths –Target table movable horizontally/vertically for alignment TBID multiplicity detector 2 horns (horn and reflector) –Water cooled, pulsed with 10ms half-sine wave pulse of up to 150/180kA, 0.3Hz, remote polarity change possible Decay pipe: –1000m, diameter 2.45m, 1mbar vacuum Hadron absorber: –Absorbs 100kW of protons and other hadrons 2 muon monitor stations: muon fluxes and profiles CNGS Secondary Beam Line

now2008 Paola Sala for the CNGS SBWG Neutrino Flux CC event rate 600  CC/kt/ pot 5.5 e CC/kt/ pot. Nominal intensity : pot/y Simulated neutrino fluxes at GranSasso : see ( also linked from

now2008 Paola Sala for the CNGS SBWG : first commissioning – beam and simulation checks in muon pits –first beam to GranSasso : problems and solutions –reflector cooling circuit –reflector striplines –radiation damage 2008 : running again

now2008 Paola Sala for the CNGS SBWG muon pit instrumentation 60cm 270cm 11.25cm 2 x 37 fixed monitors (Ionization Chambers) 2 x 1 movable monitor LHC type Beam Loss Monitors Stainless steel cylinder Al electrodes, 0.5cm separation N 2 gas filling

now2008 Paola Sala for the CNGS SBWG The Polarity asymmetry During commissioning: Observed asymmetry between Neutrino (focusing of positive mesons) And Anti-neutrino (focusing of negative mesons) The asymmetry is clearly visible in the horizontal direction There is a (smaller) asymmetry also in the vertical direction NOTE that The secondary beam has been aligned so to have CENTERED muon distributions in the NEUTRINO mode

now2008 Paola Sala for the CNGS SBWG The solution Possible explaination: the Earth magnetic field If we assume a simple offset-dipole field, and calculate the B components in the CNGS reference system: –Z along the beam pointing to GranSasso –X in the horizontal direction, pointing left * when looking towards LNGS –Y almost vertical pointing up we have: B x = Gauss = T B y = Gauss = T B z = Gauss = T On a 1 km path this field gives a deviation of a few tens of centimeters (dep. on energy), deflecting Positive particles to the left and up Negative particles to the right and down Attenuation in the Decay Tube Stainless Steel has been evaluated: Attenuation of transverse field : 2.39 Attenuation of parallel field : 1.11 What about shielding by Stainless Steel ?

now2008 Paola Sala for the CNGS SBWG The solution confirmed Simulated response of the muon monitors, in electrons/ pot, with earth magnetic field and a 1mm horizontal displacement of target vs horn/reflector The asymmetry is perfectly reproduced The absolute comparison of simulation and muon pit data is within 5% in 1 st pit

now2008 Paola Sala for the CNGS SBWG 2 nd pit In the 2 nd pit there is a 20% underestimation in neutrino mode.

now2008 Paola Sala for the CNGS SBWG works 1 : horn/reflector cooling Leak in water outlet of cooling circuit of reflector after 4·10 5 pulses (Oct 06)  Design fault in ceramic insulator brazing  Repair and exchange possible –Replace brazed connections by connections under pressure –Detailed dose planning, tooling and training –Additional local shielding  total integrated dose: 1.6mSv new old All horn and reflector outlets exchanged Water inlet circuits : installation of a more reliable solution to prevent future problems

now2008 Paola Sala for the CNGS SBWG works 2: reflector striplines Aug 2007: Cracks in busbar flexible connection of reflector New design during shutdown 2007/08 for horn and reflector old new Old design: twisted cables New design: continuous plates, clamped.

now2008 Paola Sala for the CNGS SBWG Works 3:radiation issues CNGS: no surface building above CNGS target area  Large fraction of electronics in tunnel area During CNGS run 2007, after 7.9·10 17 pot : –Failure of ventilation system installed in the CNGS tunnel area due to radiation effects in the control electronics (SEU due to high energy hadron fluence) Temperature Probes Ventilation Units Target Chamber Service Gallery Proton Beam Line Electronics Racks 2007 layout

now2008 Paola Sala for the CNGS SBWG Radiation issues solved Modifications during shutdown 2007/08: move as much electronics as possible out of CNGS tunnel area Create radiation safe area for electronics which needs to stay in CNGS High-E (>20 MeV) hadron fluence for a nominal year 2006/ < 10 6 h/cm 2 /yr 10 7  10 9 h/cm 2 /yr Simulated shielding attenuation factors between 10 3 and 10 6 for Absorbed dose 1-MeV equivalent neutrons High energy hadrons Dose monitors in electronics areas: No counts above the background coming from activated air ! for comparison: h >20MeV from cosmic rays at sea level : ≈ 10 5/ cm 2 /y

now2008 Paola Sala for the CNGS SBWG Layout Modifications 2008 TT41 TSG41 TCC4 TSG4 TCC4

now2008 Paola Sala for the CNGS SBWG Concrete, concrete bricks, movable plugs TSG4 mobile plug in TCV4

now2008 Paola Sala for the CNGS SBWG Plans for CNGS 2008 Startup : 18 June 2008 First month: gradual intensity increase up to maximum intensity : 4·10 13 pot/cycle REACHED June-November : 122 days 80 % efficiency……. Super-Cycle: contains 3 CNGS cycles –Day SC: 48s long: –1 long FT (15.6s), 3 CNGS(18s), 1 LHC pilot (8.4s), 1 MD (6s) –Night & WE: 42s long: – 1 long FT (15.6s), 3 CNGS(18s), 1 LHC pilot (8.4s) –Night & WE: 33.6s long: until LHC needs beam on a regular basis –1 long FT (15.6s), 3 CNGS(18s)  PLANNED FOR 2008 : pot

now2008 Paola Sala for the CNGS SBWG 2008 : beam monitoring  pit 1 central detector response vs time charge/pot stable ! pot/extraction: max reached beam size instability detected in  -pit 10 %

now2008 Paola Sala for the CNGS SBWG 18kV cable repair MD PS magnet exchange & septum bakeout MD SPS timing fault: vacuum leak & magnet exchange Horn water filter exchange, Hadron stop sump emptying CNGS Total Integrated Protons on Target Sep-2008: 0.57 · pot Efficiency was lower than expected!: ≈ 40 % New 2008 estimate: 1.7 · pot

now2008 Paola Sala for the CNGS SBWG Conclusions All CNGS modifications were successful The facility is running smoothly An intensity of pot per cycle has been reached Up to OPERA saw 399 events in bricks  consistent with expectations (see OPERA talk) The efficiency of the accelerator system was lower than expected, lowering the foreseen total intensity to pots for 2008 However, efficiency went back to 75% in the last weeks..  in 2009: 4 CNGS cycles per super-cycle? still to be discussed…

now2008 Paola Sala for the CNGS SBWG end

now2008 Paola Sala for the CNGS SBWG Backup slides

now2008 Paola Sala for the CNGS SBWG CNGS - FLUKA Simulation Dose in Gray for a nominal year (4.5 E19 pot) Present situation (no shielding) Situation in 2008 (with shielding) TSG4 : < 10  Gr/y TCV4 : < 100 mGr/y F 10 6

now2008 Paola Sala for the CNGS SBWG CNGS - FLUKA Simulation 1 MeV n-equiv fluence for a nominal year (4.5 E19 pot) Present situation (no shielding) Situation in 2008 (with shielding) TSG4 : < 10 6 n/cm 2 TCV4 : < 10 9 n/cm 2 F 10 6

now2008 Paola Sala for the CNGS SBWG CNGS - FLUKA Simulation High-E (>20 MeV) hadron fluence for a nominal year (4.5 E19 pot) Present situation (no shielding) Situation in 2008 (with shielding) TSG4 : < 10 6 h/cm 2 TCV4 : < 10 8 n/cm 2 F 10 4

now2008 Paola Sala for the CNGS SBWG Expected Radiation Levels Absorbed dose Neutron fluence (1-MeV equiv) Energetic hadrons (>20 MeV) fluence [Gy/y][/cm 2 /y] TSG situation – no shielding1    10 9 Shielding attenuation factor Expected levels –    10 5 TCV situation – no shielding1    Shielding attenuation factor Expected levels    10 8

now2008 Paola Sala for the CNGS SBWG Horizontal target scan- Data taken from Ionization Chambers (IC) mounted outside the shielding  Also very sensitive, backup for TBID