# Agenda for 1211/03 Femtosecond Thursday meeting at 1:00 pm in 6-1105

Steve\-\--IVID

Dave/Daniela\-\-\--M1 update

Steve\-\--W11 magnetic measurements

**Minutes.**

Steve reported that Sumitomo have submitted their quote for the IVID.
The costs are as previously reported in their budgetary estimates with
an additional \$34K for the added scope of the pressurized hot water
system. Shipping costs were not indicated. The present estimate includes
shipping by sea.

Dave presented the analysis results for the M1 mirror for the Soft Xray
beamline. The edge cooled design, which is the scope of the current
estimate, has a tangential to surface slope peak of 22 micro radians,
and a maximum temperature of 52deg. C. (reference temperature is 25 deg.
C.) The design target slope is less than 10 micro radians rms which must
also include slope errors from the polishing operation which are on the
order of 1.5 micro radians. These numbers were for 400mA beam current.
Operation of edge cooled mirrors with much lower temperatures than this
has been problematic on the HHMI beamlines. Dave also presented results
for two gun drilled design options and for the frit bonded face plate
design, both at 400mA, and at 750mA beam current. These designs gave
much improved calculated performance results. A full table of the
analysis results is distributed with these minutes. It is considered
that the gun drilled and frit bonded face plate designs will have
similar costs. The gun drilled design does not have joints at the
regions of stress, the frit bonded option does not have the joint on the
neutral axis and the geometry can produce stress concentrations. Bending
stresses are also a consideration. For these reasons the frit bonded
design is considered higher risk than the gun drilled option. The issue
is that this mirror is located very close to the fast valve and a
catastrophic failure will contaminate the ALS storage ring. Alan asked
if a worst case scenario could be identified. We have two silicon face
bonded mirrors operating at the ALS and similar designs are working at
SSRL, all have worked well so far but all are isolated from the storage
ring vacuum by a Be. Window. It was decided that this issue would be the
primary topic of our meeting next week that should be attended by ALS
management. Daniela was asked to prepare a presentation for this meeting
that clearly identified all issues for each design option.

Steve presented the W11 magnetic measurements status. At the minimum gap
of 12mm a peak field value of 1.96T was measured; the fundamental is
1.93T. The target value for the fundamental was 1.90T; the required
value is 18.2T, which corresponds to a gap of approximately 13.5mm. The
horizontal trajectory was calculated from *B~y~* measurements. RMS
deviation from a straight line is 27 micron, compared to a required 20
micron. After a single shim was installed this was reduced to 8.6
micron. The field integral for *B~y~* was within 100 G­cm over a range
--15mm\<x\<15mm. Variation of *B~x~* over this range is 150 G-cm.. The
"magic fingers" have not as yet been used. Steve commented that these
results are the best we have achieved to date. Rms phase errors were
reported to be 2.6 degrees; this will easily meet the requirements.
Christoph brought up the issue of vertical trajectory errors. This had
been discussed at the review. Steve commented that *B~x~* has been
measured, but it is very difficult to extract a believable trajectory
from results, due to cross talk with the dominant *B~y~* component. More
thought is needed on this question. There was some discussion of the
alignment of the Insertion Device in the storage ring, particularly with
reference to the back tangent port.

**Action Items (Updated)**

Steve/Ross/Ben/Alan\-\--plan for W16 after removal from the ring.

Steve/Bob -- alignment of W11 in the storage ring (relative to the
back-tangent port and e-beam

Steve -- assessment of W11 vertical trajectory errors

Phil\-\-- M1 mirror---worst case failure scenario.

Daniela\-\-\-\--prepare presentation on M1 situation for next meeting

Daniela\-\-\-\-\--check the aperture upstream of the carbon filter.

Dave, Russell, Steve,\--submit scope , cost estimate, and schedule
documentation for final approval.

Phil\-\--schedule Chopper design review with vendor..

David\-\--establish the shielding requirements for Top Off operation
with Rick Donahue

Alan/Bob\-\-\--reconcile ALS funding plan with the requirements of the
scope and schedule.

Christoph\-\-\--Conclude longitudinal field harmonics study by end of
September.

All -- risk mitigation plans

All\-\-\-\-\--update review presentation book.

Check options for W16 cost recovery with Gavin Robillard\-\-\--Alan

(Steve reports from Robillard that if another national lab expresses
interest in W16, we can only expect them to pay incidental costs of
removal from the ring, packing, shipping etc.)