Evolving document for discussion

Preliminary draft, still needs to be expanded, perhaps including:

• goal of phase 2 tests
• notes from phase 1 commissioning run, e.g.
  • plots of online display
  • use of BPM data
  • pictures from Begbroke?
• discussion of instrumentation required for phase2 - especially spot size, position.

• ATF2_2nd_phase_test_beam_v2.doc: Initial draft of document for phase 2, diagrams, tables and plots by Luis and George

• ATF2_2nd_phase_test_beam_v3.doc: New version (v3) Clarification of one of the labels in one picture and extra table of energy deposition without the target.

• ATF2_2nd_phase_test_beam_v4.doc: Version including the photon fluence for both cases (target and no target)

• ATF2_2nd_phase_test_beam_v5.doc: Version with iron beam dump instead of Lead (the correct one, I hope is the last one).

• Final version (_v6 - only cosmetic changes) to for discussion with Terenuma-san, is now on DamageTestProposals topic.

Please comment and add updates

Timescale

We need to establish if we can do this test at ATF2 (permission from ATF), if we have funding/permission from UK. Can we use this test to help with collimator damage detection system?

Initial thoughts

A few random thoughts, please add to this list!

• Radiation Safety Document for ATF2: we need this to be worded to allow this test and at an appropriate level of radiation.
  • What is the allowed level of radiation, how thick a target would we like to use ideally?
• Remind ourselves what the amplitude and frequency of vibration expected is (see DamageTestProposals) What is the profile of the shock wave at the measuring surface of the collimator, how rapidly does it vary with distance along the surface, is it symmetric?

• VISAR
  • We measure at a single point with the VISAR, is this sufficient? I would have thought we take many readings at different locations along the sample from single shot operation at nominally the same charge and beam size to build up a picture. --Main.GeorgeEllwood
  • The measured amplitude may differ from predictions e.g. because we are actually measuring at a different position relative to the beam impact.
  • We would need to phase lock the VISAR's position (on movable table) to that of the manipulator to allow us to move the target sample
  • Pulse by pulse, we would need to know accurately the impact position

• Sample
  • Thickness, materials, geometries
  • Inclusion of several wires (to one side?), of different thicknesses?
  • Current monitor or photon detection downstream for edge finding

• Expected effects
  • How does mounting sample on manipulator and VISAR on stage affect vibration? Can test in UK

• Funding
  • Are there actions we can take to mitigate lower budgets, e.g. remote operation?
  • Is there any h/w which we expect to need (if test goes ahead) which can be purchased before end of FF07/08?

-- NigelWatson - 23 Feb 2008

ATF2 Beam dump

From the discussions with Urakawa-San and Terunuma-San, due to radiation safety and prior committments to ATF2, the only location we are likely to get is in the beam dump and even then we face severe restrictions on what we can do. We will need to include lots of shielding around our vacuum chamber and enclose the air inside.

Using the drawings from Terunuma-San, I've drawn up the beam dump in 3D. Download Autodesk Inventor Viewer 11 from here to view the files I've posted:

http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=7333738

(If the link doesn't work google autodesk inventor 11 viewer)

If you download all the files and then open beamdump.iam from that directory it should work, I've tested it on my PC.

I'll try to get some more drawings that give details of the concrete shielding and the beam line in relation to the dump, that should give more of an idea how much room we have to play with.

Next Steps

Our two biggest challenges would appear to be getting the correct optics and finding a way to perform the test that satisfies the ATF radiation safety. I would suggest that before we start any major procurement or other planning exercises we run simulations based on the likely optics we can achieve. The plan for the simulations would be as follows:

James predicts the smallest beam size we are likely to achieve, taking the dispersion and emmittence values used on 29/02/2008 as well as the values from the earlier runs, this should give us a spread of beam sizes dependant on the beam conditions. If at all possible to get a round beam it makes the ANSYS/AUTODYN simulations a lot easier.

Luis takes the beam sizes from James as well as the likely charges and runs Fluka to give us the energy deposition, assuming a target of 0.6rl Ti-6Al-4V.

George takes Luis data and runs simulations on ANSYS/AUTODYN. Speak to Chris Densham or Richard Brownsword on the capabilities of the VISAR and see if it is likely that we will see any results. I would imagine we would want atleast 1 order of magnitude better resolution on the VISAR than what we expect to see from the simulation results.

If all the above steps go to plan and we look likely to see interesting results then we can start worrying about the harder job of how we perform the test at ATF2.

-- GeorgeEllwood - 29 Feb 2008

• ATF2_2nd_phase_test_beam_v5.doc: ATF2_2nd_phase_test_beam_v5.doc