MEIC Detector and IR Integration
Vasiliy Morozov, Charles Hyde, Pawel Nadel-Turonski
MEIC Detector and IR Design Mini-Workshop, October 31, 2011
MEIC Primary “Full-Acceptance” Detector
7m
(approximately to scale)
detectors
solenoid
ion dipole w/ detectors
IP
0 mrad
electrons
50 mrad
2m
2+3 m
electron FFQs
2m
Detect particles with angles
down to 0.5o before ion FFQs.
Need up to 2 Tm dipole in
addition to central solenoid.
Central detector, more detection
space in ion direction as particles
have higher momenta
Detect particles with angles
below 0.5o beyond ion FFQs
and in arcs.
Make use of the (50 mr)
crossing angle for ions!
Central detector
RICH
Cerenkov
HTCC
EM Calorimeter
4-5 m
Solenoid yoke + Hadronic Calorimeter
Tracking
2m
3m
EM Calorimeter
Hadron Calorimeter
Muon Detector
Solenoid yoke + Muon DetectorTOF
2m
Pawel Nadel-Turonski & Rolf Ent
Distance IP – electron FFQs = 3.5 m
Distance IP – ion FFQs
= 7.0 m
(Driven by push to 0.5 detection before
ion FFQs)
Interaction Region: Ions
Final Focusing
Block (FFB)
Chromaticity Compensation
Block (CCB)
Beam Extension
Section
7m
βymax ~ 2700 m
βx* = 10 cm
βy* = 2 cm
• Distance from the IP to the first FF quad = 7 m
• Quad strengths of FF triplet at 100 GeV/c
– Q1 = -64.1 T/m
– Q2 = 64.5 T/m
– Q3 = -17.0 T/m
• ±10 cm quad aperture allows clear line of sight at ±0.5
• CCB next to FFB for chromatic correction
Whole Interaction Region: 158 m
Tracking Through FFB
• Maximum excursion in X plane for positive particle
• At lower p/p values, maximum x occurs in the 2nd quad; at higher p/p values,
maximum x is in the 3rd quad
• p/p is equivalent to (q/m), i.e. p after d break up behaves as p/p = -0.5
Maximum Orbit Excursion vs Momentum Offset
• Quad aperture = Field at the pole tip / Maximum field gradient
G4beamline Simulations
• GEANT 4 toolkit for beam line simulations
• Realistic simulations of complete system at later design stages
• Not very well suited for optimization tasks
p/p = -0.5
p/p = 0.0
p/p = 0.5
Detector Solenoid
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•
•
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4 T field at the center, 5 m long, 2.5 m inner radius, IP 2 m downstream from edge
Realistic solenoid model: many infinitely-thin current sheets evenly spread radially
Ion beam at IP is at 50 mrad to the solenoid axis
60 GeV/c proton orbit distortion at the entrance into the spectrometer dipole 5 m
downstream of IP assuming proton and electron orbits are in horizontal plane at IP
– x = 250 mm, y = -8.9 mm, px/p = 0.050, py/p = -0.0024
Correcting Orbit Distortion
• Important to correct vertical offset and angle to make the orbit flat in the ring
• Tricky because no space for corrector dipoles between IP and downstream FFB
• Suggested solution:
– Rotate the interaction plane by a certain angle around the solenoid axis
– Rotate the spectrometer dipole around its axis by a certain angle
• Other options
– Let the ion orbit shift inside the FFB quads and correct it downstream
– Install FFB quads at an angle to keep the distorted orbit centered
– Make the spectrometer dipole a few independent dipoles used as correctors
– Shift the IP
– ??
– Combination of some of the above options
Suggested Solution
• Was shown in simulations to correct the vertical orbit distortion for 60 GeV/c protons
with 50 mrad crab crossing angle but should work in general
• The spectrometer dipole is modeled as a 1 m long box with 2 T uniform vertical field
• The rotation angles are first obtained analytically and then checked in simulation
• The required rotation of the interaction plane around the solenoid axis is 36.8 mrad
– Can be done by corrector dipoles in front of the solenoid where there is space
• The required spectrometer dipole rotation around its axis is -57.7 mrad
– Perhaps can be implemented without mechanical rotation by using additional coil
windings in the dipole to rotate the field
– Dipole axis lies in horizontal plane
– For the dipole model used, the correction is not sensitive to the dipole axis
alignment in horizontal plane
• In the solenoid model used, the solenoidal fringe field extends into the dipole and was
not taken into account when calculating the correction, therefore there is a small
effect from the fringe field, field maps should be used for more accurate simulations
Corrected Orbit
Final Focusing Block
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•
•
Distance from the IP to the first quad = 7 m
Quadrupole lengths: L1 = L2 = L3 = 1.5 m
Quad strengths @ 100 GeV/c: Q1 = -64.1 T/m, Q2 = 64.5 T/m, Q3 = -17.0 T/m
 x  10 cm
 y  2 cm
Tracking through FFB
FFB Acceptance Study
• 60 GeV/c proton beam originates at the interaction point
• Beam particles uniformly distributed within a horizontal (vertical) angle of 1 around
the beam trajectory and p/p of 0.7
• Quad aperture radii = 10 cm  6 T / (field gradient @ 100 GeV/c)
• Particles that pass through the FFB shown in blue
Optimized FFB
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•
•
Distance from the IP to the first quad = 7 m
Quadrupole lengths: L1 = 1.2 m, L2 = 2.4 m, L3 = 1.2 m
Quad strengths @ 100 GeV/c: Q1 = -79.7 T/m, Q2 = 41.3 T/m, Q3 = -23.6 T/m
 x  10 cm
 y  2 cm
Pawel Nadel-Turonski & Alex Bogacz
Tracking through Optimized FFB
• Each quad aperture = B max / (field gradient @ 100 GeV/c)
Optimized FFB Acceptance
• 60 GeV/c protons, each quad aperture = B max / (field gradient @ 100 GeV/c)
9 T max
6 T max
12 T max
FFB Acceptance for Neutrons
• Neutrons uniformly distributed within 1 horizontal & vertical angles around
60 GeV/c proton beam
• Each quad aperture = B max / (field gradient @ 100 GeV/c)
6 T max
9 T max
12 T max
Complete System
• Detector solenoid
– 4 T field at the center, 5 m long, 2.5 m inner radius, IP 2 m downstream from edge
• Small spectrometer dipole in front of the FFB
• FFB
• Big spectrometer dipole
– 4 m downstream of the FFB, sector bend, 3.5 m long, 60 mrad bending angle,
20 cm square aperture
System Acceptance for Neutrons
• Neutrons uniformly distributed within 1 horizontal & vertical angles around
60 GeV/c proton beam
• Each quad aperture = 6 T / (field gradient @ 100 GeV/c)
System Acceptance for p/p = -0.5
• Protons with p/p = -0.5 uniformly distributed within 1 horizontal & vertical angles
around the nominal 60 GeV/c proton beam trajectory
• Each quad aperture = 6 T / (field gradient @ 100 GeV/c)
System Acceptance for p/p = 0.0
• Protons with p/p = 0.0 uniformly distributed within 1 horizontal & vertical angles
around the nominal 60 GeV/c proton beam trajectory
• Each quad aperture = 6 T / (field gradient @ 100 GeV/c)
System Acceptance for p/p = +0.5
• Protons with p/p = +0.5 uniformly distributed within 1 horizontal & vertical angles
around the nominal 60 GeV/c proton beam trajectory
• Each quad aperture = 6 T / (field gradient @ 100 GeV/c)
Transverse Coordinates for p/p = -0.5
• 30 GeV/c protons, each quad aperture = 6 T / (field gradient @ 100 GeV/c)
• Blue: within cone with polar angle < 0.25; green: 0.25 <  < 0.5; red:  > 0.5
At the entrance into the big dipole
At the exit from the big dipole
Transverse Coordinates for p/p = 0.0
• 60 GeV/c protons, each quad aperture = 6 T / (field gradient @ 100 GeV/c)
• Blue: within cone with polar angle < 0.25; green: 0.25 <  < 0.5; red:  > 0.5
At the entrance into the big dipole
At the exit from the big dipole
Transverse Coordinates for p/p = +0.5
• 90 GeV/c protons, each quad aperture = 6 T / (field gradient @ 100 GeV/c)
• Blue: within cone with polar angle < 0.25; green: 0.25 <  < 0.5; red:  > 0.5
At the entrance into the big dipole
At the exit from the big dipole
Separation of Electron and Ion Beams
Beam Parallel after FFB
• FFB: quad lengths = 1.2, 2.4, 1.2 m, quad strengths @ 100 GeV/c = -79.6, 41.1, -23.1 T/m
• 1.2 Tm (@ 60 GeV/c) outward-bending dipole in front of the final focus
• 12 Tm (@ 60 GeV/c) inward-bending dipole 4 m downstream of the final focus
Momentum & Angle Resolution
• Beam parallel after the final focus
• Protons with p/p spread launched at different angles to nominal 60 GeV/c trajectory
• Red hashed band indicates 10 beam stay-clear
Momentum & Angle Resolution
• Beam parallel after the final focus
• Protons with p/p spread launched at different angles to nominal 60 GeV/c trajectory
• Red hashed band indicates 10 beam stay-clear
|p/p| > 0.03 @ x,y = 0
Momentum & Angle Resolution
• Beam parallel after the final focus
• Protons with different p/p launched with x spread around nominal 60 GeV/c trajectory
• Red hashed band indicates 10 beam stay-clear
Momentum & Angle Resolution
• Beam parallel after the final focus
• Protons with different p/p launched with x spread around nominal 60 GeV/c trajectory
• Red hashed band indicates 10 beam stay-clear
|x| > 2 mrad @ p/p = 0
Beam Focused after FFB
• FFB: quad lengths = 1.2, 2.4, 1.2 m, quad strengths @ 100 GeV/c = -89.0, 51.1, -35.7 T/m
• 1.2 Tm (@ 60 GeV/c) outward-bending dipole in front of the final focus
• 12 Tm (@ 60 GeV/c) inward-bending dipole 4 m downstream of the final focus
Pawel Nadel-Turonski & Charles Hyde
Momentum & Angle Resolution
• Beam focused after the FFB
• Protons with p/p spread launched at different angles to nominal 60 GeV/c trajectory
• Red hashed band indicates 10 beam stay-clear
Momentum & Angle Resolution
• Beam focused after the FFB
• Protons with p/p spread launched at different angles to nominal 60 GeV/c trajectory
• Red hashed band indicates 10 beam stay-clear
|p/p| > 0.005 @ x,y = 0
Momentum & Angle Resolution
• Beam parallel after the final focus
• Protons with different p/p launched with x spread around nominal 60 GeV/c trajectory
• Red hashed band indicates 10 beam stay-clear
Momentum & Angle Resolution
• Beam parallel after the final focus
• Protons with different p/p launched with x spread around nominal 60 GeV/c trajectory
• Red hashed band indicates 10 beam stay-clear
|x| > 3 mrad @ p/p = 0
|x| > N/A @ p/p = 0
Future Plans
• Design optimization, e.g. acceptance of the FFB using genetic algorithm
• Integration into the ring optics, such as decoupling, dispersion
compensation, understanding effect of large-aperture quadrupoles on
the optics, etc.
• Hybrid permanent / electro magnet electron FFB design?
(Pawel Nadel-Turonski & Alex Bogacz)
• Evaluation of the engineering aspects, such as magnet parameters,
electron and ion beam line separation, etc.