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MOLLER Spectrometer Update
Juliette M. Mammei
MOLLER Collaboration Meeting May 8,9 2014
2
Future Priorities (from last meeting)
• Physicist input to engineering (highest priority)o Magnetic force studieso Sensitivity studieso Design of the water-cooling and electrical serviceso Radiation doses (brought up by companies)
• Optimization of the opticso He bag/central beam pipeo Multiple magnetso No negative bendo Iron in coils
• Engineering work (MIT/Bates)o Design of support structureo Vacuum vessel design
Lower priority
MOLLER Collaboration Meeting May 8,9 2014
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• Forces with asymmetric coils
– http://ace.phys.virginia.edu/MollerSpectrometer/297 (Jason)– http://ace.phys.virginia.edu/MollerSpectrometer/298 (Juliette)– http://ace.phys.virginia.edu/MollerSpectrometer/299 (Juliette)– http://ace.phys.virginia.edu/MollerSpectrometer/300 (Juliette)
• Radiation dose on coils
– http://ace.phys.virginia.edu/MollerSpectrometer/305 (Tyler)– http://ace.phys.virginia.edu/MollerSpectrometer/306 (Seamus)
• Coil sensitivities
– http://ace.phys.virginia.edu/MollerSpectrometer/287 (Sakib, Juliette preliminary)– http://ace.phys.virginia.edu/MollerSpectrometer/308 (Tyler)– See slides
• Support Structure– See slides
• Vacuum vessel– See slides
Bids
MOLLER Collaboration Meeting May 8,9 2014
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Forces
NewOld
Coil offForces on coil to beam left with adjacent coil off
MOLLER Collaboration Meeting May 8,9 2014
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Forces
Old
New
Coil
off
MOLLER Collaboration Meeting May 8,9 2014
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Sensitivity Studies• Need to consider the effects of
asymmetric coils, misalignments etc. on acceptance
• This could affect our manufacturing tolerances and support structure
• Have created field maps for a single coil misplaced by five steps in:– -1° < pitch < 1° – -4° < roll < 4° – -1° < yaw < 1° – -2 < r < 2 cm– -10 < z < 10 cm– -5° < φ < 5°
Axes in frame of single coil
MOLLER Collaboration Meeting May 8,9 2014
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Slopes give, for example,
Then , the uncertainty in z allowed
What are the relevant ,, ,
Our ability to determine in that septant may also be important.
We’ll measure a certain rate R and asymmetry A in each septant. We assume the allowable uncertainty on A to be 0.1 ppb
Sensitivity Studies
MOLLER Collaboration Meeting May 8,9 2014
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Asymmetry vs. position offset
Asymmetry vs. rotation offset
MOLLER Collaboration Meeting May 8,9 2014
Preliminary Results
11
Fit to plots is given by
in range where approximately linear
Mean Asymmetrya (ppb) b
Z 31.75 -0.01 ppb/cmR 31.75 0.34 ppb/cmT 31.74 -0.01 ppb/degree
Roll 31.72 0.04 ppb/degreeYaw 31.75 0.06 ppb/degreePitch 31.77 -0.13 ppb/degree
= -9.24cm = 2.94mm = -17.86° = 2.28° = 1.59° = -0.75°
where
Then, for example,
(>10 cm over magnet length)
What about physical constraints?
MOLLER Collaboration Meeting May 8,9 2014
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MOLLER Collaboration Meeting May 8,9 2014
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Closest approach
MOLLER Collaboration Meeting May 8,9 2014
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Summary• These results have some simulations with same random seed
(statistical uncertainty is not as good as it seems)– Need to re-run those simulations and redo the results– All plots vs. offset treated as linear, though some clearly are not
• Very preliminary results show order ~3 mm sensitivities (not sub-mm)
• Need to look at the effect of tracking algorithm with incorrect maps
• What is the most important parameter – what is it that will determine the sensitivity – A background correction done incorrectly?– The mean asymmetry, as I’ve assumed here?– The mean θlab, which will go into the extraction of sin2θW?
MOLLER Collaboration Meeting May 8,9 2014
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Neutron shielding
MOLLER Collaboration Meeting May 8,9 2014
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Radiation dose
MOLLER Collaboration Meeting May 8,9 2014
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Support Structure
MOLLER Collaboration Meeting May 8,9 2014
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Frame Design
MOLLER Collaboration Meeting May 8,9 2014
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Vacuum Chamber design
MOLLER Collaboration Meeting May 8,9 2014
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Cut away views
MOLLER Collaboration Meeting May 8,9 2014
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Stress and deformation analysis
MOLLER Collaboration Meeting May 8,9 2014
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Bids?
MOLLER Collaboration Meeting May 8,9 2014
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Extra Slides
MOLLER Collaboration Meeting May 8,9 2014
24(Rate weighted 1x1cm2 bins)
Tracks in GEANT4 for nominal field
Mollers
eps
MOLLER Collaboration Meeting May 8,9 2014
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MOLLER Collaboration Meeting May 8,9 2014
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Slopes give, for example,
Then , the uncertainty in z allowed
What are the relevant ,, ,
We’ll measure a certain R and A in each septant. What matters is our ability to determine in that septant.
𝑄2=4𝐸𝐸 ′ 𝑠𝑖𝑛2𝜃𝑙𝑎𝑏
2
𝛿𝑄2=(𝜕𝑄2
𝜕𝐸 )2
(𝛿𝐸 )2+( 𝜕𝑄2
𝜕𝐸 ′ )2
(𝛿 𝐸 ′ )2+( 𝜕𝑄2
𝜕𝜃 𝑙𝑎𝑏)2
(𝛿𝜃𝑙𝑎𝑏 )2
MOLLER Collaboration Meeting May 8,9 2014
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Assuming
𝛿𝑄2=(𝜕𝑄2
𝜕𝐸 )2
(𝛿𝐸 )2+( 𝜕𝑄2
𝜕𝐸 ′ )2
(𝛿 𝐸 ′ )2+( 𝜕𝑄2
𝜕𝜃 𝑙𝑎𝑏)2
(𝛿𝜃𝑙𝑎𝑏 )2
The uncertainty on is:
~ 0.001 GeV ~ 0.001 GeV
~ 1.33 GeV2/rad
𝛿𝑄2
1.33𝐺𝑒𝑉 2/𝑟𝑎𝑑=𝛿𝜃𝑙𝑎𝑏=
(0.005 ) ( .0058GeV 2 )1.33𝐺𝑒𝑉 2/𝑟𝑎𝑑
=2×10−5𝑟𝑎𝑑
zcoll = 590cm
ztarg,up = -75cmztarg,center = 0cmztarg,down = 75cm
θlow = 5.5mradθhigh = 17mrad
Rinner = 3.658cmRouter = 11.306cm
From center: From downstream:
θlow,cen = 6.200mrads θlow,down = 7.102mradsθhigh,cen = 19.161mrads θhigh,down = 21.950mrads
Finite Target Effects
Rinner
Router
ztarg,downztarg,up ztarg,center
θlow,up
θlow,down
θhigh,up
θhigh,down
Assume 5.5 mrads at upstream end of target, instead of center
MOLLER Collaboration Meeting May 8,9 2014
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Looking downstream
x
y
φ=-360°/14
φ=+36
0°/1
4
S
B
r
φIn this septant:
By ~ Bφ
Bx ~ Br
By
Bx ByBx
MOLLER Collaboration Meeting May 8,9 2014
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GEANT4• Moved to GDML geometry description• Defined hybrid and upstream toroids• Parameterized in same way as the TOSCA models
MOLLER Collaboration Meeting May 8,9 2014
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GEANT4 - Collimators
MOLLER Collaboration Meeting May 8,9 2014
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GEANT4 – Acceptance definition