1. US LHC Accelerator Research Program
BNL - FNAL- LBNL - SLAC
Accident Simulations in Phase II Secondary Collimators April, TeV => 1.0 MJ TeV => 2.2 MJ
L. Keller

2. SLAC Damage Test
Beam entering a few mm from the edge of a 30 cm long copper block
The length and depth of this melted region is comparable to the ANSYS
simulation for the LHC accident.
30 cm
500 kW beam
0.65 MJ
in 1.3 sec
Beam diameter
~ 2000 µ
It took about 1.3 sec to melt thru the 30 cm block, but for this relatively large beam, the front two radiation lengths remain intact.

3. Tevatron Accident – 2003 Beam Lost on Stainless Steel Collimator
Energy deposition ~0.5 MJ
groove is 25 cm long, 1.5 mm deep

4. secondary collimator - causing it to melt within a substantial volume.
LHC : A kicker failure can deposit 9 x 1011 protons (8 bunches) on any metallic
secondary collimator - causing it to melt within a substantial volume.
Missteered beam 9x1011 protons,
1 MJ on secondary Jaw
Copper
Jaw
120 cm
melting
25-30 cm
3D ANSYS model, E. Doyle
above Cu melting

5. Cross Section at Shower Maximum Showing Copper Melting and Possible Fracture Regions in a Mis-steering Accident
7 TeV, 8 bunches
Copper
Jaw
2.5 cm
Fracture zone,
radius = 7 mm
Melting zone (grey),
radius = 3.3 mm

6. FLUKA/ANSYS Simulation of 7 TeV Accident, 1.0 MJ
Zoom in at Shower Maximum, Z = 20 cm
Melted/vaporized zone
4 mm
Zoom
6 mm
2.5 cm
Temp (ºC)

7. 7 TeV, 8 bunches, 1 MJ Accident Case – jaw adjacent to
the one being directly hit, ≈ 4 mm gap.
This jaw may be damaged too.
Copper
Copper
Fracture at 200deg C
840 deg C

8. 7 TeV, 8 bunches
Another accident Case – Beam hits
the horizontal primary collimator
The first jaw in the downbeam secondary
collimator (40m away) probably OK.
Copper
Copper
250 ˚C

9. ANSYS Simulation of Permanent Deformation in 7 TeV Accident 1.0 MJ
J. Amann
E. Doyle
Virtually no deformation at phi = ±90º
Beam side
47 µm
X (m)
Back side
upbeam
end
downbeam
end
Z (m)

10. 450 GeV Errant Beam Scraping the TT40 Vacuum Chamber - 2004
(Goddard, et.al., AB-Note BT)
2.2 MJ
Side of Beam Impact
Vacuum Chamber Wall Opposite from Beam Impact

11. FLUKA/ANSYS Simulation of Injection Accident, 2.2 MJ
Cut at Shower Maximum,
Z = 15 cm
Melted/vaporized zone
Zoom
6 mm
9 mm
2.5 cm
J. Amann
E. Doyle
Temp (ºC)

12. ANSYS Simulation of Permanent Deformation in 450 GeV Accident 2.2 MJ
J. Amann
E. Doyle
Virtually no deformation at phi = ±90º
X (m)
110 µm
Beam side
Back side
upbeam
end
downbeam
end
Z (m)

13. Instantaneous Water Pressure Bump
Cooling Tubes 2.5 cm Transverse to Beam Impact
Copper yield ≈ 300 bar
1.0 MJ
Pressure (bar)
2.2 MJ
Pressure (bar)

14. Summary and Conclusions
1. For 1 7 TeV impacting the edge of a copper cylinder,
a) The vaporized/molten zone is ~4 mm deep x ~6 mm high.
b) The permanent deformation is ~50 µ toward the beam axis.
The cooling water pressure bump is 6 bar.
2. For GeV impacting the edge of a copper cylinder,
a) The vaporized/molten zone is ~6 mm deep x ~9 mm high.
b) The permanent deformation is ~110 µ toward the beam axis.
The cooling water pressure bump is 25 bar.
3. Accident experience at other accelerators has shown that nearby vertical surfaces are splattered with metal droplets a fair distance above and below the beam axis, so that when moving to a fresh surface a rotatable jaw is preferable to raising or lowering the vertical surface.