Status of Solid

1. Status of Solid

2. PAC Report: Jan 2010 Individual Proposal Report Proposal: PR12-10-007 Scientific Rating: Title: Precision Measurement of Parity-violation in Deep Inelastic Scattering Over a Broad Kinematic Range Spokespersons: P. Souder Recommendation: Approval

3. Proposal PR12-10-007: This proposal to use Parity Violating Deep Inelastic Scattering to measure the electroweak (especially axial vector) couplings of quarks has the potential to provide precise and valuable information on a unique combination of Standard Model couplings, as well as study higher twist effects and charge symmetry violation. This experiment requires a major solenoidal detector (SoLID) the acquisition of which would create a facility generating further experimental proposals, see also PR12-10-007. The PAC believes the mission of this and future experiments using SoLID are sufficiently important that the Laboratory should make every effort to assist in securing the necessary funding. This experiment is Approved.

4. Motivation: The goal of the proposal is to perform precision studies of parity violation in deep inelastic scattering in Hall A using a new solenoidal spectrometer, named SoLID. The experiment addresses three physics topics, namely a search for higher twist effects in nucleon scattering at high x, a precision measurement of the electroweak mixing angle, and a study of charge symmetry violation in the nucleon. The results from this experiment will address issues in electroweak physics that are, notably, relevant to the NuTeV anomaly, though this is not a primary motivation. In addition, the experimental program has relevance to other projects being considered in the nuclear and high-energy physics communities. The issues addressed by this proposal lead naturally to electroweak physics studies that could be relevant to a high luminosity Electron Ion Collider. The stringent requirements on electron beam polarimetry (0.4% precision) are of relevance to polarimetry at a future International Linear Collider.

5. Issues: The experiment is a large installation proposal, similar in scope and size to the Moller experiment. A major risk in the proposal is to identify, or cost, a moveable solenoid for Hall A. PAC34 flagged the interference with staging the existing approved experimental program. We found the experimentalists responsive to the issue of having to run the experiment in stages. Higher twist uncertainties, an issue also flagged by PAC34, are difficult to calculate as well as being a motivation for the experimental program. The proponents organized a workshop on the issue, partially in response to these concerns. The theoretical issues remain a challenge. But, at present, there is no data on the issue. The only results that exist up to now come from the old SLAC E122 experiment. A 6 GeVJLab experiment in Hall A will provide some additional data on parity violation, and the experiment has just finished collecting data; however, the experiment only covers two kinematic points at relatively low x and Q2. If higher-twist effects are found to be small and manageable, this would increase the impact of the electroweak physics test. If the higher twist effects are found to be sizeable, they open up a new study for understanding nucleon structure at high x. Knowledge gleaned from a study of charge symmetry violation and the d/u ratio at high x will be complementary to other searches for the high x behavior of nucleon structure functions.

6. PAC Questions Hi Paul and KK, As I am sure you know, I was assigned as the referee for your proposals at the upcoming PAC. These have already been approved, so I am guessing that the only issue for the PAC concerns grading. I do not have any detailed questions on the documents for now. However, I would not mind learning a little more about the review process and timing: (1) Beyond this PAC, what further reviews do you expect to address for the lab? Technical, etc?? (2) What is the rough timeline until the experiment is online, namely (a) when will the design be done (b) when will construction begin (c) how long will construction take (d) when might the first run/runs of the experiment be scheduled? I am just asking for your best guess.

7. Cont. (3) For the Moller experiment, three run periods are planned. What about SoLID? How many individual runs? How will the parity proposal share with the 3He proposal by Haiyan et al.? (4) How does the funding look generally for the construction? Does the experiment require extra NSF or DOE grants for the equipment or is everything to be built coming out of the Jlab budget? Sorry for the late request for this information, but these should be fairly general questions and not too hard. I am just trying to get more sense of where the projects are after approval. Cheers, Emlyn

8. E-mail During PAC Hi Paul, Just to be official: We would like to see the impact on the various SoLID measurements with only half the beamtime (electroweak mixing, HT, d/u, charge symmetry violation). Also, please do particularly show a comparison of the statistical and systematic uncertainties on sin2thetaw versus the original proposal. Thanks, Emlyn

9. Response One possible plan to use beam time most efficiently would be first to run half of the statistics for deuterium. If at that stage we see no kinematic dependence on the asymmetry, either in x or Q^2, and if the result agrees with the Standard Model, the motivation to continue would be greatly reduced. Prospects for explaining NuTeV would be remote and further running would have minimal impact on our C_2 error. Hence we would want to run hydrogen next. On the other hand, if the data indicate that the CSV is significant, the proposed running time on deuterium would be highly motivated.

10. Changing Experiments Floor Time Required to Change Experiments We plan to mount the detectors on the downstream pole piece of the solenoid, which can be quickly removed as discussed in PR-10-007. Removing them should take on the order of a week. Removing the cryostat should take more time, which would be on the order of two months. This step is required for switching to any other experiment.

11. PAC37 Results

13. Moller Schedule • Jan 2009: Approved by PAC • Jan 2010: Director’s Review • Dec 2010: Meeting with DOE • Jan 2011: Approved for 344 Days • Summer 2011: Proposal to Doe • ?? CD0;

14. Prepare for Directors Review • Theory Issues (Begin with NLO Analysis) • Monte Carlo • Specify Hardware • Cost Moller: Mostly Engineering SoLID: Mostly Physicists