Questions & Answers


Talk by Steffen Kappler

	Questions & Answers

Q (M. Capeans):

Wonderful talk! I see that somehow the Triple-GEM seems to be less sensitive to aging than other detectors. Does this mean that you can relax the cleanliness conditions of the final gas system at Compass?

A (S. K.): No. The cleanliness and conditions for the final gas system can not be relaxed.

Q (H. Kolanoski): Did you do aging tests in hadronic beams? I want to remind you that, for example, low energy alpha's are not equivalent to hadronic beams which can initiate nuclear fragmentation.

A (S. K.): Beam test were performed in hadronic beams.

Q (A. Romaniouk): What can you say about the different aging for the 2 chambers (SWPC vs. GEM) ?

A (S. K.): Since the SWPC was installed in the same gas line, but behind the GEM detector, the drop of gain in the SWPC might be explained by the presence of outgassing/ polymerization products (to which the GEM was insensitive, but not the SWPC)

Q (B. Schmidt): Was there ever an observation of aging in a GEM detector and what does it look like?

A (S. K.): Yes, a GEM detector can be operated in conditions, where aging occurs.

Q (J. Va'vra): A response to B. Schmidt's question if anybody has seen an aging effect with a GEM:
Yes, I did, in C₂H₆+TMAE. If one sparks, one may develop a conducting path along the kapton (> 10 MOhm).

Q (J. Va'vra): Do I understand that you do not have any oil bubbler at the output, i.e. just a long tube?

A (S. K.): Yes, there was no bubbler.