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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)
Cen
ter
Pix
el S
ign
al (
Arb
)C
ente
r P
ixel
Sig
nal
(A
rb)
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).
Tot
al C
harg
e (A
rb)
Tot
al C
harg
e (
Arb
)T
otal
Cha
rge
(A
rb)
Tot
al C
harg
e (
Arb
)
Tot
al C
harg
e (
Arb
)T
otal
Cha
rge
(A
rb)
Tot
al C
harg
e (
Arb
)T
otal
Cha
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(A
rb)
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