1) Report of Cherrill Spencer from IHEP, China, on ATF2 quad production
2) Updated results on 14mrad extraction line tracking -- Yuri Nosochkov
3) Evaluation of possibility of self shielding detector -- Lew Keller
4) Considerations of collider hall sizes and self-shielding assembly for SiD -- Tom Markiewicz
Cherrill is reporting from IHEP that production of ATF2 quads goes well.
Machining the core of the first quad is finished -- the new EDM was used to
machine the poletips, the dimensions were measured and tolerances were found all
acceptable. Machining of the rest of the cores can now continue. The first 4
trim coils have been wound and they look good.
The main conductor is due to arrive on December 20th (from Finland) and then winding will start. Goal is to have first coil wound and potted by December 30th. A video conference is planned for January 3rd/4th to look at the first coil-- which will have to be cut in half so we can see the turns are sitting correctly and the impregnation has been done properly.
Yuri presented updated results for 14mrad extraction regarding beam loss on
the collimators. The problem was found in DIMAD which has the wrong definition
of collimators: it treats RCOLL as ECOLL, and vice versa. So the previous result
corresponded to square collimators, even though they were assigned as ECOLL. The
updated tables 4,5 (in the Nanobeam paper) now have round collimators. This
increased the collimator loss but mostly for cases with large delta_y. Also, the
new cases (14, 23, 24) for 14 mrad line are included.
It was discussed that although the losses on collimators 1-3 are acceptable, there may be further optimization, in particular, increasing somewhat the size of beam dump window could reduce the losses. This will be studied.
Lew presented studies of IR hall shielding using program SHIELD 11. Worst
case accident full beam hitting a thick target in IR hall was assumed. SLAC
rules require instantaneous dose rate < 25 Rem/hr for this worst case, credible
accident. This was the assumption for SLD self-shielding. Therefore the sum of
all neutron and photon sources must be less than 25 R/hr. Some of the
conclusions are the following:
The removable wall between detectors for a single push/pull hall does not have to be 5 m thick.
For a shallow hall with no self-shielding, the roof over the detector needs to be about 2 m thick
In ILC the high energy neutrons cause the most trouble, suggesting that more steel and less concrete is indicated.
Self-shielding detector for ILC should be possible provided that the issue of cracks (gaps) could be solved.
In the ILC self-shielding case, there do not need to be walls in the IR or a concrete roof over the pit in a shallow site.
Tom presented considerations of collider hall sizes and sizes for pacman
(self-shielding of detector) for SiD. This will be discussed at the end of this
week at SiD
workshop at Fermilab. In the second version of the talk, the pacman was
split in two parts -- mobile and fixed. Further optimization, toward decreasing
size of the detector hall (presently L48*W28*H30 m), has been discussed.
Andrei Seryi, 12/15/05