1. OFFICE OF SCIENCE Office of High Energy Physics, Cosmic Frontier Mid-Scale Dark Energy Spectroscopic Instrument (MS-DESI) Experiment Fermilab PAC Oct. 16, 2012 Kathy Turner DOE, Office of Science, Office of High Energy Physics

2. Dark Energy program planning  MS-DESI Pro-actively developing an independent, balanced, staged, robust HEP program Supernova Surveys, BOSS and DES  LSST  and beyond  With near term and low cost options, using multiple methods & staged implementation and science results First step was a community study to look at the science reach of current and planned projects; then to identify key missing components and opportunities for reaching full “Stage-IV” levels Science case for a HEP program developed by a task force at HEP request (Rocky Kolb, chair). Their Aug. 2012 report identified key missing components and opportunities in progressing to a stage IV program with multiple methods: There is compelling case for an advanced wide-field spectroscopic survey, which would enable dark-energy information at the Stage IV level through the techniques of Baryon Acoustic Oscillations and Redshift Space Distortions. A spectroscopic survey would produce Important dark-energy science results in the period between the completion of the Stage III Dark Energy Survey (DES) photometric project and the arrival of results from the Stage IV LSST photometric project.  This science plan used was used to support our program: CD-0 for a mid-scale dark energy spectroscopic instrument (MS-DESI) experiment was signed 9/18/12.

3. MS-DESI - status & plans We are going forward with planning for MS-DESI. The earliest we could request MIE funds to begin fabrication would be in the FY14 President’s Budget Request. Note: Important that this experiment get done to fill in the gap between DES ending and LSST starting data-taking. At least two collaborations are proposing to develop a MS-DESI: BigBOSS in the North (Mayall telescope at Kitt Peak) DESpec in the South (Blanco Telescope at CTIO) Facilities: The major consideration is which telescope facility to use and requires close coordination with NSF-AST. Need to concentrate on this since outside constraints may determine which path we take.

4. MS-DESI path forward HEP has started regular discussions with NSF-AST to understand their plans so we can use as input to our process. What are possible opportunities and models for the experiment? What are processes, constraints, impacts with other communities?  The ball is in the Agencies’ court: NSF-AST Portfolio Review said a plan for divesting telescopes should be in place by the end of 2013 -- We expect to have guidance for the community on the facility in the near term For any case: We will want to optimize the experiment: technology, science, survey strategy, costs, etc.