Re: April 2009

1.  The Princeton group continued fabrication of the RPC bubbler system and control electronics.

2.  The proposal to monitor the isobutane concentration in the RPC gas by gas chromatography has been described in DocDB#3458 and 3484.
[Results of a 2-week demonstration of this scheme are presented in DocDB#3557, May 7, 2009].
This proposal has been OKed by Dana Beavis and Xiaonan Li, and will be sent to the Export Control Officers for review shortly.

3.  The Daya Bay offline software has been successfully installed on the Princeton HEP cluster, and various mock data runs were made throughout April.

4. Qing He has contributed to improved simulation of radioactive decays in the AD (DocDB# 3425 in March, #3451 in April and #3540 in May).

5.  Studies of possible aging of the RPCs continue, and in April an RPC with the equivalent of 5 years of operation at Daya Bay was opened and examined via a high-quality optical microscope.  Some dramatic "age spots" were noted, as will be described in detail in a future DocDB note.

--Kirk