1. Recommendations of 12/16/05 review committee & SLAC response
LARP Phase II Secondary Collimator RC1 Prototype Engineering Status 3/28/06
Recommendations of 12/16/05 review committee & SLAC response
Double the engineering effort
Consider bi-metallic jaw to limit deformation
Evaluate plastic deformation
More detailed engineering before fabricate test
Info needed from CERN
Accident Case – damage estimates
LARP LHC PHASE II SECONDARY COLLIMATOR CD1 STATUS - E. Doyle 28 Mar /9

2. Engineering Effort - Manpower
FNAL candidate bowed-out
Former LBNL engineer interviewed
Expect final agreement any day
Designer – candidates interviewed, job offered
LARP LHC PHASE II SECONDARY COLLIMATOR CD1 STATUS - E. Doyle 28 Mar /9

3. Review: Baseline and Alternate Jaws
BEAM
WATER
Review Committee: fill in core with SST “strongback”
Fabrication Method
Strongback not included
Alternate configuration
- risky mechanically
- lower deflection ~ 100 um SS
Baseline configuration
- lower risk
- more deflection ~ 400 um SS
LARP LHC PHASE II SECONDARY COLLIMATOR CD1 STATUS - E. Doyle 28 Mar /9

4. Baseline jaw – added SST and Cu core
NOTE: Cu yield strength = 44MPa
Conclusions
- Yielding is a problem, deformation not evaluated yet, use Glidcop (yield ~ 250MPa)
SST core no improvement (same CTE as Cu, lower conductivity)
Cu core helps (conductive shortcut – reduces DT across jaw)
LARP LHC PHASE II SECONDARY COLLIMATOR CD1 STATUS - E. Doyle 28 Mar /9

5. Detailed engineering
RC1 Concept as presented to reviewers: Flexible end supports with central gap-defining mechanism
Stop prevents thermal bowing of jaws from intruding on minimum gap
Leaf springs allow jaw end motion up to 1mm away from beam
LARP LHC PHASE II SECONDARY COLLIMATOR CD1 STATUS - E. Doyle 28 Mar /9

6. X Detailed Engineering Review Committee concerns
tilt stability of flexible end supports
accuracy of jaw placement
lack of jaw indexing concept
cooling/thermal stability of central stop, springs, etc (implicit)
SLAC’s Planned Response
- quantitative understanding of CERN positioning mechanism
- understand calibration & operation of CERN positioning mechanism
- size support springs (force to neutralize 400um deflection ~ 30kN, force to slip stepper ~ 2kN, => need larger stepper and/or softer jaw support springs)
- response of springs/stop/positioning mechanism in all operating regimes X
LARP LHC PHASE II SECONDARY COLLIMATOR CD1 STATUS - E. Doyle 28 Mar /9

7. Info Needed from CERN
Introduction to fabrication vendor (jaws, vac tank, positioning mechanism)
Drawings of support structure for 0o, 90o and skew orientations. We need to know operating clearances for tank/jaw positioning mechanism (scale assembly drawings or part details to make our own assembly)
Verbal description of jaw calibration and control algorithms (Aberle Nov 4, 2005 presentation)
Standing request
New
LARP LHC PHASE II SECONDARY COLLIMATOR CD1 STATUS - E. Doyle 28 Mar /9

8. Accident case: Tevatron collimator damage
“The beam groove is probably on the order of a 1/16” (1.5 mm) deep and the main part of the spatter extends 1” (25 mm) or more to either side of the groove. The damaged collimating surface is a vertical surface. The largest of the splatter beads is on the order of 1/16”. “
Estimated energy deposited < 0.5 MJ
LARP LHC PHASE II SECONDARY COLLIMATOR CD1 STATUS - E. Doyle 28 Mar /9

9. Accident case simulation
New ANSYS simulation of accident case
8 bunches of 1.1e11, 7 TeV protons
1 MJ in 200 ns
bin size .156e-3 in x, .2e-3 in y
heat of fusion modeled, not heat of vaporization
peak temperature ~ 58e3 C
region at shower max exceeding melting point (in gray) 3.3mm deep x 5.2 mm wide
LARP LHC PHASE II SECONDARY COLLIMATOR CD1 STATUS - E. Doyle 28 Mar /9

10. LHC Phase II Collimation
BONUS SLIDES
LARP LHC PHASE II SECONDARY COLLIMATOR CD1 STATUS - E. Doyle 28 Mar /9

11. Material Properties
LARP LHC PHASE II SECONDARY COLLIMATOR CD1 STATUS - E. Doyle 28 Mar /9

12. Interesting side trip: 64% less distortion if cooling is limited to a 36o arc centered on beam path.
360o full I.D. cooling
36o arc cooling
Note transverse gradient causes bending
89C
Note axial gradient
61C
dx=221 mm
Spec: 25mm
support
dx=79 mm
Note more swelling than bending
64% less distortion
LARP LHC PHASE II SECONDARY COLLIMATOR CD1 STATUS - E. Doyle 28 Mar /9