**DRAFT-3^rd^ Harmonic Monday Meeting Minutes-DRAFT**

**Date: October 29, 2007**

**Time: 9:00 A.M.**

**Place: Hermitage**

[Attendees (P=Present, Ph=attended by phone):]{.underline}

  --------------- --- --------------- --- -------------- --- ------------ ---
  T. Arkan            H. Edwards      P   D. Olis        P   G. Wu        P

  L. Bellantoni       M. Foley        P   P. Pfund       P   John Z.      P

  H. Carter           E. Harms        P   S. Reeves      P   E. Vogel     

  M. Champion     P   A. Hocker       P   L. Ristori         J. Li        

  L. Cooley           H. Jiang        P   A. Rowe        P   L. Alsip     P

  C. Cooper       P   T.              P   N. Solyak          D.           P
                      Khabiboulline                          Sergatskov   

  N. Dhanaraj         D. Mitchell     P   Y. Torun                        
  --------------- --- --------------- --- -------------- --- ------------ ---

Minutes recorded by Dan.

Minutes are posted at:
<http://tdserver1.fnal.gov/dolis/39GHz_minutes.html>

3.9GHz Project page is: [www-a0.fnal.gov](../www-a0.fnal.gov)

## Meeting Minutes

9-cell Cavity status

-   Mike reports that cavity-8 was baked on Friday and now is with Timer
    for tuning. It is scheduled for etch late this week. Cavity-7 is
    done and shipped on Wednesday last week from JLAB. It is not rec'd
    yet and Mike is trying to track it down.

Single cells

-   In house fab'd: Mike reports that he is welding on flanges this
    week. End tubes are being formed this week.

-   Vendor fab'd: Scott reports that he believes he resolved QA issues
    with Roark.

Helium Vessels

-   Mike reports that current plan is to weld vessel onto cavity-5 next
    Wed. but many things need to get done to allow this. Due to a
    tolerancing issue, he had to have WHS touch up end tanks for proper
    fit to bellows. He is working on weld samples. Also, Mike is
    concerned about heat from welding damaging the bellows and WHS is
    machining a copper "chill plate" so sink heat to prevent this. He
    hopes to have this Wednesday. Timer will check field flatness of
    cavity-5 after vessel is welded on.

-   Mike showed one of Dan W.'s weld samples to Kay Jench and another
    visiting engineer from DESY to get some input on slight
    discoloration of weld. They surmised that perhaps the argon purge
    line had a leak and that some O2 was back-streaming in. Welder in
    fact found a leak, repaired it, and subsequent welds looked much
    better.

-   Linda reports that first article helium vessel is expected late next
    week from HiTech. Don will go and check setup prior to weld, perhaps
    during sample welding.

Couplers

-   Dan reports that coupler test stand assembly work is proceeding at
    A0 with trimmed cold end antennas. The captive silicon bronze
    fastener that holds the inner conductor to the cold end antenna
    seized up after about 6 turns to remove it during test stand
    disassembly. Fastener had to be forced out and threads on screw were
    rolled. No explanation yet.

-   Dan reports that warm end of coupler installed on HTS/cavity-1 last
    Monday. Coupler installation was difficult due to misalignment of
    cold end coupler to vacuum vessel flange. PPD Survey group took some
    measurements. When Dan receives the data, he will discuss with
    Valeri P. how to modify support of cavity to allow alignment after
    installation. Dan will work on a simple survey tool.

Other Business

-   Andy reports that HTS has been pumped down and leak-checked. Waiting
    for safety approval to cooldown cavity-1. Klystron has been moved
    from A0 and installation at Meson with waveguide is progressing.
    Timer warns that RF power needs to be limited during test since
    cavity HOM caps are leaky to RF. Stray RF could damage other
    instrumentation in the cryomodule.

-   Transportation fixture for cavity cold mass is expected today. Don
    reports that plan is to ship dummy cavity string to IBC. Mike McGee
    will do \~1wk of vibration studies and then it will be disassembled.
    Many components on the cold mass assembly will be modified per
    suggestions from Kay J., et al.

-   Helen hopes to have a review before Thanksgiving regarding shipping
    cryomodule to DESY.

-   Charlie presented some test results on tumbled, single-cell 3.9 GHz
    cavity. It was tumbled in industry using centrifugal barrel
    polishing and KEK media. Removed 60-80 microns of material in
    tumbling. First VTS after 20micron etched showed x-rays at about 11
    MV/m. Charlie suspected not all of the tumbling media had been
    removed from cavity and had 40microns more etched, x-rays
    disappeared in subsequent test. The cavity reached approximately 19
    MV/m after the second test. During the second test a loose antenna
    tip affected coupling. Plan is to retest on Wednesday.