Alberto Guglielmi Istituto Nazionale di Fisica Nucleare, Sezione di Padova CNGS neutrino beam: from CERN to Gran Sasso from design to installation of CNGS beam-line CNGS neutrino beam calculation CNGS beam commissioning... a long term study with P.R. Sala and A. Ferrari A. Guglielmi, NOW6, September -5, 24.
& & ' % & & % ) 5, - - 2 Foreword CNGS CERN to Gran Sasso neutrino beam: designed for appearance in a pure experiments with for over the rate of detected the energy! at ev km is () oscillation search looking for the beam as observed in atmospheric neutrinos and K2K, MINOS, oscillation probability oscillation events +* /43 spectrum of./ parameter in! $# ev : well matched to GeV to maximize the signal rate range. : P osc *σ (arbitrary units ) - ν µ at GS (p.o.t. GeV m 2 ) - x -9.45.4.35.3.25.2.5..5 5 5 2 25 3 35 4 45 5 E ν (GeV) CNGS beam at CERN SPS: s from decay of CNGS design: accomplished on the experience of the previous WANF 6, 7produced by 4 GeV/c protons on C target NOMAD which resulted in a strong benchmark for conventional neutrino beams both WANF and CNGS beams benefit of hadron production measurements of SPY (Secondary Particle Yields) experiment dedicated to neutrino beam production study beam for CHORUS and A. Guglielmi, NOW6, September -5, 24. 2
8 9 < CNGS neutrino beam-line 4 GeV/c protons extracted CERN SPS, directed on a carbon target where mesons are copiously produced positive (negative) secondary mesons: focused (defocused) by magnetic Horn + Reflector in km decay tunnel toward Gran Sasso Lab where are generated in the decay in flight of two He bags to minimize meson absorption before the decay residual mesons are absorbed in a massive C+Fe dump at the end of the beam line proton beam intensity: # ;: p.o.t/year, shared (dedicated) operations 6 s and 7 s A. Guglielmi, NOW6, September -5, 24. 3
23/6/3 6/3/4 2/9/3 A. Guglielmi, NOW6, September -5, 24. 4
%? % @ % A 8 < = CNGS proton beam two fast extractions of 4 GeV/c protons every 6 s, interleaved by 5 ms, for a total of # spatial, angular profile of proton spills: : 8# : ppp in pot/y, ultimate intensity: mm, # : mrad s ppp (tested) A. Guglielmi, NOW6, September -5, 24. 5
9 < ) J K ) L CB DE I graphite target... FHG pot/y,.52 MW! revolver target magazine : 5 He tubes with inserted nominal + spare targets nominal target: 3 graphite rods, cm each for a total 3.3, 8mm, mm the first 2, the more fired, to better dissipate heat first 8 rods: separated by 9 cm each to better develop meson production last 5 rods: packed to reduce longitudinal smearing in 6production for a better focalisation can works at # M: ppp,.75 MW, for M: A. Guglielmi, NOW6, September -5, 24. 6 pot/y (dedicated beam operation)!
horn Nreflector J 9 R VT R 7 P Z Horn OReflector, toward Gran Sasso by a pulsed currents m each, magnetic lenses to focus TS U KA and 6QP WYX Horn: at.2 m from target to maximize angular acceptance/ focusing Reflector at 42 m from target to complete the higher energy particle focusing A. Guglielmi, NOW6, September -5, 24. 7, in the 3-5 GeV range KA
internal conductors: parabolic shape, only.8 mm thickness to minimize absorptions/reinteractions but sufficient for mechanical stability no material in between inner/outer conductor! A. Guglielmi, NOW6, September -5, 24. 8
A. Guglielmi, NOW6, September -5, 24. 9 Reflector and decay-tube installation
` ] \ [ CNGS: conventional beam from pion and kaon decay to predict the beam flux and composition at Gran Sasso site precise description of: 6^] _ 7 yields in -target interactions focusing (defocusing) of positive (negative) secondaries and their propagation/decay in the beam-line, development of hadronic interactions and cascades (reinteractions...) 4 main sources of neutrinos: proton interacting in proton target 6 ] _ 7 _ 7 : _ V _ V V V V V a ] protons missing target: interactions in the materials along the beam-line: prompt neutrinos from charm and K decays in the target and dump: particle reinteractions in the materials of the beam-line: affecting and, mainly... a conventional [-beam is a complicated cascade of physical processes! A. Guglielmi, NOW6, September -5, 24.
k b c j e point for high energy [central beam calculation: -target experimental data (Be): NA2 ( 8) 4 GeV/c, SPY ( 99) 45 GeV/c, M.C. hadronic generators: the most suitable, FLUKA (2), dfe gih gih g C CC % accuracy % accuracy at 45 GeV/c π + /(p.o.t.*sr*%) 4 3 π /(p.o.t.*sr*%) 4 3 2 2 - - -2-2 -3.5..5.2 θ(rad) -3.5..5.2 θ(rad) production from 45 GeV/c proton on cm Be target: FLUKA ( ), NA2/SPY rescaled data (l) sensitivity on oscillation searches limited by hadronic cross-section knowledge! to improve the beam description and reduce the systematics: tuning of the FLUKA Be meson yields to NA2, SPY data with reweighting functions... A. Guglielmi, NOW6, September -5, 24.
Comparison with the WANF data (NOMAD L = 84 m) m V V V 7 m m V m P a P 8 a 9 a BCT SEMs Al Collimator Reflector Muon Pits Decay BCT2 Horn Tunnel Earth CHORUS Be Target 45 GeV/c protons TDX collimator Iron Shield NOMAD ν µ / 3 GeV / 9 p.o.t. ν e / 3 GeV / 9 p.o.t. 6 ν µ 5 4 K + 3 K L π + 2 µ - 5 5 2 Neutrino energy (GeV) 4 ν e 3 K + 2 µ + K L 5 5 2 Neutrino energy (GeV) ν µ / 3 GeV / 9 p.o.t. ν e / 3 GeV / 9 p.o.t. 5 ν µ 4 K - 3 2 µ + π - K L 5 5 2 Neutrino energy (GeV) ν 3 e 2 K L µ - K - 5 5 2 Neutrino energy (GeV) : npo : 7 %, : %, :.3 %, nqo r o r o correct reconstruction of: - - - : from 6 P : from 6 : from _ 7 _ 7 _ 7 prediction of _ 7 GeV the main background for NOMAD! 7(: GeV 8GeV 9GeV +... decays +... decays +... decays 7, and P search in V ) which was A. Guglielmi, NOW6, September -5, 24. 2
V _ u V t { Vw xw ` j G \ \ [ ƒ ƒ [ [ [ NOMAD data at CERN WANF: CC, CC, s CC control-sample for s CC prompt isolated in the final state prompt isolated t in the final state charge/momentum measurements, visible energy (hadrons! 8T, syst. errors on ` 4 % at GeV/c % vleptons) zy : 4.2 % normaliz., 5 % Events / 8 GeV 8 7 6 5 4 3 2 ν e CC 2 4 6 8 2 4 6 8 2 Visible energy (GeV) very good agreement! flux: 7 % on -dep. Events / 8 GeV Events / 8 GeV Events / 6 GeV x 2 5 5 4 2 4 2 }~ ν µ CC 5 5 2 Visible energy (GeV) ν µ CC 5 5 2 Visible energy (GeV) ν e CC 5 5 j Visible energy (GeV) A. Guglielmi, NOW6, September -5, 24. 3 CC, Data / MC Data / MC Data / MC.2..9.8.4.2.8.6 2.5.5 ν µ CC 5 5 2 Visible energy (GeV) ν µ CC 5 5 2 Visible energy (GeV) ν e CC 5 5 Visible energy (GeV) CC-MC ( ) normalized to data l) (
V K 6 t CNGS beam description with FLUKA CNGS beam-line facility fully described within FLUKA for various MC simulation purposes: energy dep., radioprotection studies: mechanical stress/heating of materials, dose equivalent rate to monitor beam response,i.e. distributions at muon-pits predict neutrino beam energy spectrum/composition at Gran Sasso - Detailed geometry/composition description of beam-line from p injection to hadron-stop - including beam monitors perfectly modeling target chamber, graphite rods, supports,... - Various types of biasing, i.e. for beam simulations: decay length biasing applied to meson, muons: decay sampled every m direction from 6, 72-body decay: biased as. : 2 ˆA, Š: angle sampled to beam-direction transformed in CMS,, decay direction V and inverted for (at low : _ 7 V ) A. Guglielmi, NOW6, September -5, 24. 4
neutrino ancestors: V :7 P [-parents at the exit of rod where p interacts ` rel. ab. rel. ab..8.7.6.5.4.3.2..4.35.3.25.2.5..5 - - 2 particle type 2 particle type rel. ab. rel. ab..5.4.3.2..3.25.2.5..5 : completely dominated by 2 particle type 2 particle type 6 P a.u. a.u. 5 4 3 2 25 2 5 5 a.u. 2 3 4 p (GeV/c) a.u. 2 3 4 p (GeV/c) 4 2 8 6 4 2 7 6 5 4 3 2 2 3 4 p (GeV/c) 2 3 4 p (GeV/c) also! only.4 % of the neutrino flux from meson effects of hadr.-prod. convoluted to focusing effects, meson decay-chain produced in proton interactions out-of-target energy spectrum of in-target ancestors: and meson life-time! - spike in 6 P as effect of focusing optics - -production is effective via reinteractions A. Guglielmi, NOW6, September -5, 24. 5
) ) U U [for \ ) m Š W W W W Horn NReflector focalisation ( dœ ) at low momenta ( GeV/c): Horn focus 6 P up to 35 mrad, dn/dω.6.4.2 over-focusing for mrad; Reflector extends up to 6 mrad at higher momenta: combined angular acceptance of Horn + Reflector extends up to 2 mrad for momenta ` GeV/c dn/dω 2 5 2 4 6 8 θ (mrad) at the Gran Sasso site: flux (a.u.) 4 35 3 25 2 5 dn/dω 5 5 2 4 6 8 θ (mrad) Ž Ž the Ž! Ž flux increased by (twice than at WANF) contamn. reduced by 2 flux (a.u.) 5 3 25 2 5 2 4 6 8 E-ν µ (GeV) 5 5 2 4 6 8 θ (mrad) 2 4 6 8 E-ν µ (GeV) A. Guglielmi, NOW6, September -5, 24. 6
V 7 a V P a P š [ \ [[CC/kt/y-low V 9 Z 9 V 8 8 9 Z { t m neutrinos at Gran Sasso 3 2 5 5 Neutrino energy (GeV) - ν µ / 2 GeV / 7 p.o.t. 2-5 5 Neutrino energy (GeV) 5 5 Neutrino energy (GeV) ν e / 5 GeV / 7 p.o.t. - 5 5 Neutrino energy (GeV) ν e / 5 GeV / 7 p.o.t. # 8 8 # M ν µ / 2 GeV / 7 p.o.t. # Z 8 8# ( cm : < Flux pot) y (%) (%) o -CC expected event rate: 28 last -parent : from : from : from P 6 (97 %),7 (85 %), (47 %),7 P 6 P (3 %) (8 %),7 (39 %),7 (6 %)+... ( %) +... : from (7 %),7 (22 %) (8 %) A. Guglielmi, NOW6, September -5, 24. 7
< from [interactions in the Gran Sasso rock: a monitor for [flux interaction points uniformly sampled within a 3 m rock dept expected 8-fluence: Π: pot day (nominal beam) ICARUS T6: intensity) of which 87 with y (nominal beam o coming mainly from high energy GeV assuming a good knowledge of bulk of beam (internal interactions in T6) measurement of-fluence above 4 GeV with good statistical accuracy A. Guglielmi, NOW6, September -5, 24. 8
œ UT V R R evolution of the CNGS project optimized Horn and Reflector optics, ka, WYX V = K Z ka, thin inner conductors strongly reduced amount of material inserted in the beam-line, only žof s from terziary decays with a reinteraction downstream the target (this fraction increases up to 23 % for enhancement of keeping low 28 -CC Ÿ and s) flux at the Gran Sasso optimizing 2less than WANF): V contamination (factor spectrum for L downstream the target, appearance, are expected, a factor 2 more than the 98 conceptual design! due to the proton beam size and target configuration - positioning of proton beam on target surface - beam-line optics, horn and reflector positioning and currents,... are not critical for CNGS neutrino flux calculation at 732 km of distance using the same simulation tools successfully tested at CERN WANF the neutrino flux can be predicted at Gran Sasso site within a 9% systematics ratio within 3% normalization error plus 3 % bin-to-bin energy error (A.G., NOW-4) A. Guglielmi, NOW6, September -5, 24. 9
CNGS neutrino beam commissioning three weeks from July increasing proton intensity up to to monitor and align beam components - only : : pot used: proton beam horizontal/vertical/angular scans on the target: multiplicity optimization to check efficiency with which protons are converted into secondaries multiplicity: compare TBID signal downstream the target with beam current monitor upstream alignment of beam elements ppp, BPM2 proton position monitor + TBIDs: Sec. Emission Monitor, 2 monitoring of absolute in the muon pits downstream Hadron-stop: intensity beam horizontal/vertical profile shape beam horizontal/vertical profile center many BLMs (Beam Loss Monitor, ionization chambers), up m Ti foils, different shape +... per cm and.5 s comparison data vs expectations in order to align the different elements... A. Guglielmi, NOW6, September -5, 24. 2
) centering of proton beam, collimator and target BPM2 TBID beam a collimator target horn.9 BSI.8.6.8.7.4.2.6.5.4 p BPM2 collimator arbitrary multiplicity.8.6.3.2.4.2 p BPM2 Target Target down by.7mm. -8-7.5-7 -6.5-6 -5.5-5 -4.5-4 -3.5-3 -2.5-2 -.5 - -.5.5.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 collimator ( BPM2 [mm] 8cm): horiz. beam position scan target OUT, reading from TBID -4-3.5-3 -2.5-2 -.5 - -.5.5.5 2 2.5 3 3.5 4 BPM2 [mm] horiz. beam position scan target IN, intensity on TBID vs. BPM2 position A. Guglielmi, NOW6, September -5, 24. 2
absolute signal in first -pit PRELIMINARY 37 fixed BLM monitors + movable.4.35 meas: nominal sim: nominal.3 charges/pot.25.2.5..5-57.5-46.3-35 -23.8-2.5 -.3-9 -78.75-67.5-56.25-45 -33.75-22.5 -.25.25 22.5 33.75 45 56.25 67.5 78.75 9.2 2.5 23.7 5 5 cm 35 46.2 5 57.5.4.35 meas: nominal sim: nominal.3 charges/pot.25.2.5..5-57.5-46.3-35 -23.8-2.5 -.3-9 -78.75-67.5-56.25-45 -33.75-22.5 -.25.25 22.5 33.75 45 56.25 67.5 78.75 9.2 5 cm 2.5 23.7 5 35 46.2 5 horizontal (top) - vertical (bottom) profiles neutrino beam: well centered, good initial agreement of data vs. expectations! A. Guglielmi, NOW6, September -5, 24. 22 57.5
9 Conclusions CERN to Gran Sasso CNGS for appearance, beam was designed oscillation search looking for in ev the project was approved on December 999 civil engineering- equipment design- production and installation phases lasted 6 years and handed over to operation on 8 August 6 commissioning showed that proton beam and secondary beam parameters are within specification TOTAL: 7.6 E7 po t EXT: 3.8 E7 EXT2: 3.79 E7 Fri 8 Aug. 26 3:4 pot pot 2 days MD + problems On Friday 25 Unix time CNGS operations: : ppp, Wed. 3 Aug. 26 5: : MD Monday + CNGS smoke Detection system problem CNGS is operational - now the neutrino beam has to be carefully measured/studied the toughest and more interesting part is still ahead! thank you to all the colleagues from INFN, CERN and Laboratories all over the world who contributed to the project s success! pot A. Guglielmi, NOW6, September -5, 24. 23
back-up charges/pot.5.45.4.35.3.25.2.5..5 mrad.2mrad.25mrad.5mrad -.5mrad -.2mrad -.25mrad central muon monitor (charges/pot) E- 4 3.5 3 2.5 2.5 horn on/refl on horn on/refl off horn off/refl on Poly. (horn on/refl on) Poly. (horn on/refl off) Poly. (horn off/refl on) -58-46 -35-24 -3 - -9-78.8-67.5-56.3-45 -33.8-22.5 -.3.25 22.5 33.75 45 56.25 67.5 78.75 9.3 2.5 23.8 35 46.3 57.5 angular scans: response of BLM s in pit- target OUT cm.5-2 -.5 - -.5.5.5 2 2.5 3 3.5 4 ms timing of horn/reflector: responce of central muon monitor A. Guglielmi, NOW6, September -5, 24. 24
back-up 2 Friday 25, restart after MD.7 E 3 pot Extraction Friday 8 Extraction 2 extraction - 2 in the first operation period A. Guglielmi, NOW6, September -5, 24. 25