Comissioning the NuMI Beam at Fermilab with Ion Chamber Arrays D. Indurthy, R. Keisler, S. Kopp, S. Mendoza, M. Proga, Z. Pavlovich, R. Zwaska Department of Physics, University of Texas – Austin D. Harris, A. Marchionni, J. Morfin Fermi National Accelerator Laboratory M. Bishai, M. Diwan, B. Viren Brookhaven National Lab A. Erwin, H. Ping, C. Velissaris Department of Physics, University of Wisconsin – Madison D. Naples, D. Northacker, J. McDonald Dept. of Physics, University of Pittsburgh 4E7/cm 2 /spill 2E7/cm 2 /spill.5E7/cm 2 /spill Muon Monitors Plateau currents for 288 muon chambers Each chamber mapped with 1Ci  -source ( 241 Am, 30-60keV) Press. & Temp calibration developed Ion Chamber Calibration 1% relative calibration Uncorrected Corrected ±1% Muon Monitors  3 stations at 740,750,770m  Dolomite rocks screens lower energy particles, so subsequent alcoves see higher energy muons  9x9 array ceramic IC’s (3mm gap)  Measures position & intensity of tertiary muon beam downstream of the absorber Signal connections Aluminum Wire Gasket HV connections Kapton Cables Chambers Tray 241 Am  source Monitors flushed with He gas Hadron Monitor Measures intensity and position of the remnant hadrons from the primary proton beam Max flux ~1E9/cm2/spill, ~2E9 Rad/yr 32” 7x7 IC array, 1mm electrode separation Components Rad Tested up to 12GRad (6 NuMI years) Installed on a dual-rail support structure with remote-handling capability Beam Instrumentation Performance Studies Beam Based Target & Baffle Alignment Beam’s Eye View Graphite protection ‘baffle’ Graphite target Water cooling line target horn baffle Rail system allows variable positioning of the target w.r.t the horns  focusing different energies 3 target positions: Low energy (LE), medium energy (ME), high energy (HE) Beam Intensity (E12 ppp) Center Pixel Signal (Arb)  Mon Chamber HadMon Chamber Target Leak & Recovery Leak discovered in mid-March Resumed running in Apr. Target scans used to diagnose water level in target Water level indicated by beam instrumentation after efforts to drain target in place, confirmed with boroscope Water leak in the cooling line Attenuation from water No water Target fully drained Water fills target Beam RMS spread from multiple scattering Vertical beam Position (mm) In LE position, horns focus LE (4-6GeV)  ’s only Vertical Target Scans Beam Monte Carlo of Vertical Target Scans Baffle Target Baffle Target Baffle Target Baffle Target Baffle Target Baffle Target Baffle Target Baffle Target Scans to align the target Beam translated horizontally across the target/baffle Measure integrated charge in the downstream monitors Shape of Monitor Signal v. Beam Position on Target curve used to characterize target alignment Peaks correspond to target apertures Asymmetry .25mm target misalignment w.r.t. baffle Target 1.25mm beam-left, 1mm high (vertical scans not shown). Total Charge (Arb) LE Position HE Position Horn Studies No Water After effort to drain in place Water fills most of target Increased horn current  increased numbers of focused pions In the LE position, horn- target positions are tuned to focus mainly lower energy  ’s(4-6GeV) Beam through the apertures produce deficits of the alcoves Beam on Baffle yields muons focused by horns Beam through the apertures  more non-interacted the HM HE position  more peaked  Mon profiles All alcoves sensitive to horns with the HE beam 210m  Mon Center Pixel Operating at 300V HadMon Center Pixel Operating at 190V No change in charge collection efficiency above 40V ppp On Target Increased intensity  slower turnon Increasing Slope  intermediate water level 2D projections provide beam centroid alignment to better than 100  rad off the target Hadron Monitor Muon Monitor Vertical Horizontal Vertical In-Beam Profiles