From: Elias Metral
Sent: Friday, October 14, 2005 2:48 PM
To: Francesco Ruggiero; Frank Zimmermann
Subject: RLC meeting

Dear Francesco and Frank,

I did not dare, during our last RLC meeting, add the following points, which I need however to inform you on:



1) Meeting with Luca Bruno, Jean-Michel Fraigne, AG and Myself on TCDD and TDI. 

 

- TCDD is a kind of collimator, whose goal is to protect the cold mass of the dipole, and it is downstream of the TDI. There are 2 TCDD, 1 in IR8 (it is a fixed mask here), and 1 in IR2 (it is a movable mask there for Alice).

Impedance + trapped modes? Their priority is for the fixed. AG proposed already to continue the pipe with the same diameter and then just have to make a transition between a rectangular and a circular shape. We thus avoid the trapped modes (by decreasing the radius of the pipe we increase the frequency of the trapped modes). We told them to make this tube in Cu with good contacts and that’s all. Next meeting on 07/11/05 to discuss results of simulations by AG.

 

- TDI: Discussion about the RF screens of the LHC injection beam stopper (TDI). They are 2 screens (in Copper and with many holes) which are inserted in the TDI from both sides and then joined in the middle. They will launch the production but before that Luca wanted to show us the final drawings. 3 questions arose:

      1- There are many holes now on Cu for the outgassing (asked by M. Jimenez). What about impedances?

2- Is it possible to manufacture the holes by punching? 

3- Can two RF sheets be joined by other means than EB (Electron Beam) welding (e.g. mechanical joints)? In fact Luca told me that they will use anyway this method.

4- Is there a mandatory grade of copper to be used?

 

2) Guillaume sent me an update of the LHC collimators parameters. I will thus have to make an update of the impedance and subsequent beam stability problems.



Please, either add this to the minutes or I will mention it the next time.

Cheers,

Elias.

PS: See you for a coffee...