Sensitivity of CNGS muon

Sensitivity of CNGS muon detectors to beam-line misalignments q OUTLINE: Requirements for CNGS muon detectors Beam Loss Monitors as muon detectors Effects of beam-line alignment errors Sensitivity reach to mis-alignments 17 March 22 Francesco Pietropaolo, INFN/Padova 1

CNGS beam-line monitoring q CNGS main features: High energy beam (1-3 GeV) optimized for n t appearance No near detector envisaged n m beam normalization performed at LNGS: by experiments (OPERA/ICARUS) with large area muon detectors (n m interactions in up-stream rock) q Requirements for monitors along beam-line Detect mis-alignments of beam-line elements producing significant effects at LNGS: Proton beam wrt Target Horn / Reflector wrt beam axis Monitor beam intensity/stability (relative calibration only) 17 March 22 Francesco Pietropaolo, INFN/Padova 2

1 m 1m CNGS: location of beam monitors 7 m 67 m muons profile --> nm profile Francesco Pietropaolo, INFN/Padova 3 SEM foils Hadron profile monitors Proton wrt target Low energy m In principle alignments High energy m optics wrt p-beam alignment 17 March 22

Choice of detectors and layout for the muon monitoring stations q Detector: Choice based on results of studies on alignment errors negligible effects on n t rate with alignment errors within predicted accuracy (for all beam line elements) CERN-EP21-37; CERN-SL-21-16 EA Emphasis on reliability access to muon stations very restricted Muon pit 2 q Layout: Sample muon profile with sufficient accuracy to detect asymmetries # of detectors, spacing, Muon pit 1-3 -2-1 1 2 3 Radius (m) 17 March 22 Francesco Pietropaolo, INFN/Padova 4

BLM s as detectors for the muon monitoring stations m beam PRO: robust stable in time large signals (allow distant electronics ª 1 km) good S/N ready to use (with front-end electronics & DAQ) in modules of 36 (18x2 cables) V bias ª 1 kv CONTRA: poor linearity at highest muon flux (under investigation) gas filling (1 bar) N2 17 March 22 Francesco Pietropaolo, INFN/Padova 5

17 March 22 Francesco Pietropaolo, INFN/Padova 6 Fluka standalone Fast parametric simulation After 15 m Fe hadron dump ( 2 GeV range-out filter) After 67 m of molasse ( 5 GeV range-out filter) ª 2 m! r (m) r (m) -.5 -.25.25.5-2 -1 1 2-2 -1 1 2 p ±, p ±, K ±, m ± (1 13 pot cm 2 ) -1.4.5 1..8 1. 2. 1.5 1.2 2. 3. 1.6 un-collided proton peak m + (1 13 pot cm 2 ) -1 x 1 1 x 1 2.5 m + (1 13 pot cm 2 ) -1 Hadron monitor 7 x 1 5 4. first muon pit second muon pit BLM s characteristics: matching muon beam intensity and pit layout

17 March 22 Francesco Pietropaolo, INFN/Padova 7 Clear loss around Horn focused momenta Loss -2.8 ±.2 % First muon pit very sensitive to Horn focused particles Average displ. = 19.1 ±.5 cm Second muon pit sensitive to much higher energies Average displ. = -3.5 ± 1.2 cm E (GeV) r (m) r (m) 2 4 6-2 -1 1 2-2 -1 1 2.2.5 n t CC evts (GeV kt year) -1.4 1..4.8 1.5.6 1.2 2. 2.5.8 sin 2 2q = 1 1.6 3. Dm 2 = 2.5 1-3 ev 2 x 1-3 1. m + (1 13 pot cm 2 ) -1 n t evts at LNGS x 1 7 2. first muon pit x 1 5 second muon pit 3.5 m + (1 13 pot cm 2 ) -1 Mis-aligned case Aligned case Example 1: 6 mm horn lateral displacement (expected accuracy ª.1 mm!!) Effects of alignment errors

17 March 22 Francesco Pietropaolo, INFN/Padova 8 2 4 6-2 -1 1 2-2 -1 1 2 n t CC evts (GeV kt year) -1.2.5.4 1..4.6.8 x 1-3 1. m + (1 13 pot cm 2 ) -1.8 1.2 1.6 n t evts at LNGS x 1 7 2. first muon pit second muon pit m + (1 13 pot cm 2 ) -1 1.5 2. 2.5 3. 3.5 x 1 5 Example 2: 1 mm p-beam lateral displacement (expected accuracy ª.1 mm!!) Effects of alignment errors

Overall effects of CNGS beam-line misalignments n t CC interact. loss (%) 1 st muon chamber centroid displ. (cm) 2 nd muon chamber centroid displ. (cm) Proton beam lateral displacements (alignment accuracy ª.1mm).5 mm 1. mm. - 2.8 Proton beam angular displacements (alignment accuracy ª.1mr).5 mr 1. mr. -1.3 -.6-1.2-1.2-2.3 7.3 14.8 3.7 1.4 Small effects at LNGS Measurable along beam-line Horn lateral displacements (alignment accuracy ª.1mm) 3 mm 6 mm Reflector lateral displacements (alignment accuracy ª.1mm) 1 mm 3 mm -1. -2.8 -.4-3. 1.1 19.1 5.7 21.5 >>>> Statistical accuracy of the MC simulation <<<<.2.5 -.6-3.5-1.7-18.8 1.2 Muon monitors (complemented by SEM s at target) are sufficient to disentangle source of misalignment 17 March 22 Francesco Pietropaolo, INFN/Padova 9

Study of the layout of BLM s in the muon monitoring stations Working hypotheses: 18 BLM s per pit s meas 3% / full scale (mainly relative calibr.) max signal adjusted at full scale good linearity over full signal range Arrangements (17 BLM s): Centered on beam axis Left/Right symmetric Orthogonal Polar Estimator: Weighted sum of (L-R) differences Depends on s meas, DS, number of BLM s No need for absolute calibration! DS Goal: best arrangement best spacing (DS) minimal number of BLM s 17 March 22 Francesco Pietropaolo, INFN/Padova 1

Detecting asymmetries in muon profiles Estimators of projected displacements: depend on left/right differences along given direction Dx =  x i W i,j /  W i,j = DS  i cosq j [W i,j -W -i,j ] /  W i,j i,j i,j i>,j i,j y i q j x Dy =  y i W i,j /  W i,j = DS  i sinq j [W i,j -W -i,j ] /  W i,j i,j i,j i>,j (W ij = muon flux measurement in each detector) i,j DS Errors: s ª s DS 2 (i cosq x meas  j )2 /  W i,j i>,j i,j Estimator of sensitivity: Dr = Dx 2 +Dy 2 Dq = inv sin( Dy Dr ) s ª s DS 2 (i sinq y meas  j )2 /  W i,j i>,j i,j s q ª s r Dr = s x 2 + s y 2 Dr 17 March 22 Francesco Pietropaolo, INFN/Padova 11

Simulations q Extensive simulation of possible misalignments Proton beam wrt target - horn/reflector wrt beam-axis Focus on small displacements (sensitivity) Several displacement directions (x,y) q Wide variety of arrangements of 17 BLM s tested Orthogonal configuration 4 BML s per row Spacing for 1cm to 5cm Polar configuration 8 BLM s per circle Spacing from 2cm to 1cm Non-uniform spacing also tested Grouping BLM s where muon profiles vary rapidly x 1 7 2. q Double BLM s density (33 per muon station) also tested 1.6 1.2.8.4 muon pit 1-2 -1 1 2 x-slice (m) 17 March 22 Francesco Pietropaolo, INFN/Padova 12

17 March 22 Francesco Pietropaolo, INFN/Padova 13 4 8 12 2 7cm 2 4 6 Dr (cm) 8 Estimator Dr approaches muon profile average displacement when the full distribution is sampled Best sensitivity for minimum s r /Dr 1 Sensitivity to beam-line mis-alignments (I)

17 March 22 Francesco Pietropaolo, INFN/Padova 14 4 8 12 2.1.2 Relative error.5.4.3 7cm Best monitor spacing, DS, depends on muon profile width Polar/orthogonal configurations equivalent sensitivity Sensitivity to beam-line mis-alignments (II)

Sensitivity to beam-line mis-alignments (III) 1 st muon chamber (max spanned radius = 8 cm) Horn lateral displacements 3 mm 6 mm -1. -2.8 1.1 19.1 14% 8% 2 nd muon chamber (max spanned radius =12 cm) Proton beam lateral displacements.5 mm 1. mm s meas = 3% / full scale n t CC interact. Loss (%). -2.8 Centroid profile displ. (cm) 7.3 14.8 Relative error (%) 16 BLM s 32 BLM s 18% 1% 6% 3% 7% 4% wide variety of configurations (uniform/non-uniform spacing) give comparable sensitivity 16+1 BLM s allow detecting displ. with negligible effect at LNGS (assuming s meas = 3% / full scale) 32+1 BLM --> factor 2.5 better (more detailed description of muon profiles) 1 motorized BML for x-y scanning and cross-calibration 17 March 22 Francesco Pietropaolo, INFN/Padova 15

Summary Misalignments of the beam-line elements -within project values- will not affect n t event rate at Gran Sasso Muon monitoring arrays (based on BLM s) - located after the CNGS dump - should provide reliable information to control beam intensity and misalignments Optimization of BLM s design and layout is underway to match CNGS highest muon flux 17 March 22 Francesco Pietropaolo, INFN/Padova 16

BLM characteristics q Ionization camber Diameter 9.2cm Length 19cm Volume 1liter Filling N 2 (99.9%) Pressure 1bar Ionization energy 27eV Sensitivity 5 1-5 C/Gy Efficiency 4 1 3 pairs/part. Bias Voltage 8V (5-12V) Rise-time 3ns Dynamics > 1 6 q Electronics and DAQ Acquisition mode integration ADC full scale 1V Resolution 12bit Integrator capac. min 5pF max 5mF DAQ unit 36(+4) channels 1 CPU+Timinig Signal cables 18 channels Cable length max 15m Acqusition time 3ms (36ch.) q Performance (Cable <5m; C min = 1nF) Radiation resist. > 1 6 Gy q Calibration Single source (137Cs - 3mCi) --> few % cross-calibration & time stability Drift 1bit/s Noise 3bit Sens. 4 1 3 part./bit Full scale 1.6 17 part. 17 March 22 Francesco Pietropaolo, INFN/Padova 17