Comissioning the NuMI Beam at Fermilab with Ion Chamber ArraysComissioning the NuMI Beam at Fermilab with Ion Chamber ArraysD. Indurthy, R. Keisler, S. Kopp, S. Mendoza, M. Proga, Z. Pavlovich, R. ZwaskaDepartment of Physics, University of Texas – Austin

D. Harris, A. Marchionni, J. MorfinFermi National Accelerator Laboratory

M. Bishai, M. Diwan, B. VirenBrookhaven National Lab

A. Erwin, H. Ping, C. VelissarisDepartment of Physics, University of Wisconsin – Madison

D. Naples, D. Northacker, J. McDonaldDept. of Physics, University of Pittsburgh

4E7/cm2/spill 2E7/cm2/spill .5E7/cm2/spill

Muon Monitors

Plateau currents for 288 muon chambers

•Each chamber mapped with 1Ci -source (241Am, 30-60keV)

•Press. & Temp calibration developed

Ion Chamber Calibration

•1% relative calibration

Uncorrected

Corrected

±1%

Muon Monitors3 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

AluminumWire Gasket

HVconnections

Kapton Cables

ChambersTray241Am 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

hornbaffle

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)

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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 BaffleTarget

Baffle Baffle

Target

Baffle BaffleTarget

Baffle BaffleTarget

Baffle BaffleTarget

Baffle BaffleTarget

Baffle BaffleTarget

Baffle BaffleTarget

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 center @ 1.25mm beam-left, 1mm high (vertical scans not shown).

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LE Position

LE Position

LE Position

LE Position

HE Position

HE Position

HE 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 muons @ the alcoves

Beam on Baffle yields muons focused by horns

Beam through the apertures more non-interacted protons @ 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 Targetppp On Targetppp On Target

ppp On Target

ppp On Target

ppp On Target

ppp On Target

ppp On Target

Increased intensity slower turnon

Increasing Slope intermediate water level

2D projections provide beam centroid alignment to better than 100rad off the target

Hadron Monitor

Muon Monitor

Vertical

Horizontal

Horizontal

Vertical

In-Beam Profiles