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vacuum

700 m 100 m 1000m 67 m. vacuum. p + C  (interactions)  p + , K +  ( decay in flight )  m + + n m. CNGS secondary beam monitoring. CNGS production: p + C --> p , K --> m + n m

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  1. 700 m 100 m 1000m 67 m vacuum p + C (interactions)  p+, K+  (decay in flight)  m+ + nm

  2. CNGS secondary beam monitoring CNGS production: p + C --> p, K --> m + nm NB1. Neutrino nm events at Gran Sasso from the CNGS beam are very rare (a dozen a day…); detectors are complex, response slow -> we must monitor the beam locally, at CERN NB2. Measure the muons < - - > measure the neutrinos NB3. Understanding of the neutrino beam depends on muon detection (compare measurements to simulations); detection of secondary particles p, K after magnetic horns is “impossible” due to background

  3. “a word” about the TBID: (1) a monitor to align the target with the proton beam (in particular during commissioning): measure ratio BSI foil(s) / BCFT while moving the target (2) a monitor to observe small misalignments of the proton beam w.r.t. the target measure ratio BSI foil / BCFT while moving the target; measure L/R and U/D ratios (examples: cf. A.E. Ball et al. SL-2001-016-EA) beam pos. at target 0.5 mm off -> ratio 15% off beam angle 0.3 mrad -> ratio 15% off questions: reliability of simulations, background answer: L+R is also an intensity measurement…

  4. -> in routine operation, after commissioning, the TBID is complementary to the muon monitors – this does not mean, that the TBID is a useless monitor -> PLEASE keep studying technologies for a TBID to operate in this type of high intensity, fast extracted and well focused beams

  5. CNGS muon beam monitoring TNM41 TNM42 Two muon detector stations, separated by 67 metres of rock; rock acts as “energy filter”; muon energy cut-off in first chamber 15 GeV, in second chamber 25 GeV

  6. NOTE: Access to muon detector stations very restricted

  7. scenario protons on target (per 10.5 ms extraction pulse) peak m intensity TNM41 (per cm2and per 10.5 ms extraction pulse) peak m intensity TNM42 (per cm2and per 10.5 ms extraction pulse) setting-up 1012 2.2x106 3.3x104 nominal 2.4 x 1013 5.3x107 7.9x105 upgrade 3.5 x 1013 7.7x107 1.2x106 muon beam intensities NB. very high intensities in very short pulse – can not count muons, measure current induced in detector

  8. muon beam profiles TNM42 TNM41 NB1. muon beams are typically “meters” wide NB2. two types of simulations agree within about 20%

  9. metre-size beam distributions: -> can be measured with huge ionisation chambers (“strips” integrating all particles of a given X or Y slice needs de-convolution of information to get profiles) -> can be measured by several selected “point-detectors” (e.g. CNGS, 17 standard SPS size BLM monitors per muon detector chamber needs “fitting” to get profiles, but centroids can be obtained analytically) -> can be measured by a travelling “point-detector”, but not in 10.5 msec

  10. Sensitivity to beam-line mis-alignments using BLM’s in the muon pits: (F. Pietropaolo) meas = 3%

  11. Sensitivity to beam-line mis-alignments using BLM’s in the muon pits: (F. Pietropaolo) >> wide variety of configurations (uniform/non-uniform spacing) give comparable sensitivity >> 16+1 BLM’s allow detect displ. with negligible effect at LNGS (if smeas = 3%) >> 32+1 BLM --> factor 2.5 better (more detailed description of muon profile) >> 1 motorized BML for x-y scanning --> useful complement ! meas = 3%

  12. Summary -> muon monitoring is the CNGS “quality check”, spill by spill -> 17 fixed plus 1 motorized monitor in each of the two muon detector chambers -> access to muon detector chambers very difficult: request high reliability and (maybe) redundance -> Apologies to the TB: after discussion with the experts, we have decided to go for ionisation chambers of the type used as BLM in accelerators

  13. “loose ends” (a notion copied from H.S. -> for H.S.) (1) need replacement of J. Camas in RHWG (2) need tests of BLM at high intensity pulses (3) need confirmation that BPKG in air is possible (booster tests ?) (4) need an answer on “who does what” concerning the loose ends, i.e. various temperature measurements, protection shutter, helium gas control, decay vacuum control (5) list of controls cables needed (already late…) (6) CNGS REVIEW 28/29 April 2003 … … + probably more, hope to be seeing you soon again !!

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