1. Machine-Detector Interface
Nikolai Mokhov
Fermilab
January 8, 2014

2. Scope of Machine-Detector Interface Efforts
Developments of physics, geometry and tracking modules for adequate modeling of heat loads in superconducting (SC) magnets and particle backgrounds in Muon Collider (MC) detectors for both 125-GeV COM Higgs Factory (HF) and TeV MC.
Building unified MARS model of Interaction Region (IR), entire ring (the source of backgrounds can be as long as 1/3 of the ring), magnets and other machine components along with corresponding collider detector.
Design studies of Machine-Detector Interface (MDI) and SC magnets with thorough optimization of their component performance via full-scale Monte Carlo simulations. The goal is two-fold:
Design SC magnet protection system that reduces heat loads to the tolerable limits and helps decrease background.
Further reduce background loads on detector components to manageable levels via MDI optimization and exploitation of background hit reduction techniques in detector.
January 8, Mokhov - MDI

3. MDI in
Completion of MDI design studies for 1.5-TeV COM Muon Collider (MC) with optimized protection systems for the IR and arc SC magnets as well as for detector, with source term files provided to detector community (July- December 2012)
First round of design studies of the 125-GeV COM MC Higgs Factory (HF) with protection system proposed that exhibits feasibility of large- aperture cos-theta Nb3Sn IR and ring magnets, with manageable levels achieved for detector background loads; detailed exploration of hit rate reduction techniques for the MC detectors (January-December 2013, Overview in this talk)
January 8, Mokhov - MDI

4. MDI-Related Higgs Factory Parameters
Unit
Value
Circumference, C m
299 * cm
2.5
Muon total energy
GeV
62.5
Number of muons / bunch
1012 2
Normalized emittance, N
mmrad
0.3
Long. emittance, ||N
mm
1.0
Beam energy spread %
0.003
Bunch length, s
5.64
Repetition rate Hz 30
Average luminosity
1031/cm2/s
January 8, Mokhov - MDI

5. HF Muon Decays: Backgrounds and Heat Load
lD = 3.896×105 m, ×107 decays/m/bunch xing (2 beams)
4.8×108 decays in IR per bunch xing responsible for majority of detector background
3.08×1011 decays/m/s for 2 beams*
Dynamic heat load: 1 kW/m**
~300 kW in superconducting magnets
i.e. ~ multi-MW room temperature equivalent
*) 1.28×1010 decays/m/s for 1.5-TeV MC
**) 0.5 kW/m for 1.5-TeV MC
Note:
Large-aperture high-field magnets
(large bmax and et, reduced good field region) huge physical aperture
in IP vicinity increased loads on detector
January 8, Mokhov - MDI

6. MC Higgs Factory MARS15 Model
MARS model of SiD-like detector
with CMS upgrade-type tracker
January 8, Mokhov - MDI

7. Current HF MDI in MARS15
January 8, Mokhov - MDI

8. 50-cm ID IRQ2 and IRQ4
MARS15 Model
Nb3Sn cos-theta combined function IR quadrupole design HF collider quad lengths: 0.5 ≤ L ≤ 2.05 m
January 8, Mokhov - MDI

9. 50-cm ID 8-T IR Dipoles
MARS15 Model
Coil ID: 32 and 50 cm in IR, 27 cm in CCS and MS and 16 cm in Arc
HF collider dipole lengths: 2.25 ≤ L ≤ 4.1 m
January 8, Mokhov - MDI

10. Tungsten Liners and Masks to Protect SC Magnets and Detector
Reduce peak power density in inner Nb3Sn cable to below the quench limit with a safety margin, from a hundred mW/g to ~1.5 mW/g
Keep the HF lifetime peak dose in innermost layers of insulation below ~20 MGy
Reduce dynamic heat load to the cold mass from 1 kW/m to ~10 W/m
Suppress the long-range component of detector background
January 8, Mokhov - MDI

11. BCS1 8-T Dipole with Elliptical Tungsten Liner
Optimized individually in each magnet in the ring
January 8, Mokhov - MDI

12. BCS1: Tungsten Mask and Power Density
Geometrically tightest tungsten mask (L = 15cm) at the IP end of BCS1 dipole
Ring center
Optimized individually for each magnet interconnect region in the ring
January 8, Mokhov - MDI

13. Peak Power Density: At the Target
Ring center
January 8, Mokhov - MDI

14. Dynamic Heat Load: At the Target
“Warm” components
1.9K cold mass
January 8, Mokhov - MDI

15. Higgs Factory Nozzle Design
Expect poorer performance compared to
1.5-TeV MC: geometrically larger aperture,
almost twice shorter, substantially thinner,
2.5 times shorter trap and 3.5 longer tip-to-tip
open region (±2sz plus no extra shadowing
for collision products)
5deg
A dozen of configurations studied in
2013 in full MARS Monte-Carlo:
V1. q = 7.6deg, aperture radius R = 5s,
bare tungsten (UCLA HF WS, 03/13)
V2. q = 15deg, aperture radius R = 4s,
BCH2 cladding (MAP13, 06/13)
...
Be pipe radius increased from 3 to 5cm,
thoroughly optimized nozzle inner
shape, additional W/Fe/Concrete
shielding at MDI, tighter/thicker masks
and magnet inner absorbers (liners) …
V7x2s4. December 2013
q = 15deg
January 8, Mokhov - MDI

16. MDI Design Efficiency Visually
January 8, Mokhov - MDI

17. Particle Flux and Power Density in Q1 at z = 4.4mg n
Ring center e±
January 8, Mokhov - MDI

18. MDI Particle Flux Densityg n m e±
January 8, Mokhov - MDI

19. Backgrounds Entering Detector per Bunch Crossing
Number of particles (Eth = MeV) and Energy flux (TeV)
Particle
1.5-TeV MC
10deg
125-GeV HF v2
v7x2s4
Photon #
TeV
1.8×108
160
3.2×109
12000
2.8×108
2200
Electron #
1.0×106
5.8
1.2×108
9000
2.0×106 32
Neutron #
4.1×107
170
1.7×108
300
5.2×107 86
Ch. Hadron #
4.8×104 12
1.0×105 26
1.0×104
2.3
Muon #
8.0×103
184
2.8×103
8.2
<E>=23 GeV
<E>=3 GeV
January 8, Mokhov - MDI

20. Photon Fluence (cm-2) per Bunch X-ing
v7x2s4
January 8, Mokhov - MDI

21. Tagged Decays & Loads on VXD Barrel
v7x2s4: >10 peak reduction for g and e± compared to v2
Layer radii: 5.4, 9.45, 13.49, 17.55; cm; -20 < z < 20 cm
January 8, Mokhov - MDI

22. Background Suppression in VXD and Tracker
Carnegie Mellon University studies
with ILCRoot using 1.5-TeV MC MARS source files
Inefficiency of IP muon hits and surviving fraction
of MARS background particle hits in the VXD and
Tracker Si Detectors versus width of timing gate
for hit time resolution of 0.5 ns
4-ns gate provides a factor of a few hundred
background rejection while maintaining >99%
efficiency for hits from IP muons.
IP muon hit cluster inefficiency and surviving fraction
of MARS background hit clusters vs. energy deposition
Threshold at z=0 in innermost 200mm layer of barrel
tracker (top) and outermost 75mm layer of barrel
VXD (bottom).
A factor of 2 efficiency at best.
January 8, Mokhov - MDI

23. Beam Loss Power Distribution
SLAC HF MDI Studies (1)
Tracking studies using REVMOC and DECAY TURTLE codes One-beam loss power distribution around ring: Average power on Be beam pipe for one beam for 3 nozzle configurations:
Beam Loss Power Distribution
2-beam’s 200W on beampipe
will need cooling:
more material, more interactions
There is a room for nozzle optimization
3.5 kW on each nozzle will require
cooling system
V2 96W
V6 7W
V7 0
January 8, Mokhov - MDI

24. SLAC HF MDI Studies (2)
FLUKA model at ±25m from IP: magnets, v2-nozzle and some shielding; detector represented only as scoring planes. Results were compared against similar results from the MARS team and eventually both sets of background files were deemed compatible. The time distribution of neutrons is broader than that generated by MARS. Estimated timing-based efficiency in this simple model is lower compared to that from MARS/ILCRoot CMU group.
January 8, Mokhov - MDI

25. MDI FY14 Plans
Production runs for HF background files to feed detector community.
Documentation of MARS results on the SC magnet protection system for the HF Collider and backgrounds in the HF detector.
Build MARS model for 3-TeV MC: lattice, magnets, MDI.
Perform initial studies of heat loads and backgrounds in 3-TeV MC.
Launch massive MARS runs to design and optimize the SC magnet protection system for 3-TeV MC.
Launch massive MARS runs to design and optimize the system to suppress
backgrounds for 3-TeV MC.
Perform FLUKA and Decay Turtle studies for 3-TeV MC.
Perform studies on methods to suppress background hit rates in detector components for HF and 3-TeV MC.
January 8, Mokhov - MDI

26. IBS MDI Schedule Collider Concept Specification Interface Parameters
Technology Specification
IBS Review Ready Date
Higgs Factory
8/27/2014
12/25/2014
1/24/2015
1.5 TeV
3 TeV
4/24/2015
5/24/2015
> 5 TeV
7/28/2015
11/25/2015
12/25/2015
Ring-MDI Interface Parameters
January 8, Mokhov - MDI

27. MDI Effort and Key Personnel
Activity
Personnel
Institution
MAP FTE
MARS code development including NERSC mode
N. Mokhov, S. Striganov, I. Tropin
FNAL
0.15
MARS model of magnets, IR, ring, detector and MDI
I. Tropin, N. Mokhov
0.35
Design and optimization of MDI and magnet protection
0.45
Production runs on background source terms at MDI
S. Striganov, N. Mokhov, I. Tropin
0.25
Background rejection in detector
N. Terentiev
CMU
1.0
Decay Turtle and FLUKA modeling of backgrounds
T. Markiewicz, T. Maruyama, L. Keller, U. Wienands, J.P. Delahaye, N. Graf
SLAC
Total
2.55
Tight connection with MAP Collider (Y. Alexahin) and Magnet (V. Kashikin, A. Zlobin) WGs as well as with MC Detector group (R. Lipton, H. Wenzel, V. Di Benedetto, A. Mazzacane)
January 8, Mokhov - MDI