Dear Henk, Here are our responses to your questions about proposal 102. If you have any further questions, I will be happy to answer them. Sincerely, Larry 1. R_LT and A_LT have slightly different contents, obviously because of the contribution of R_L+R_TT+R_T in the latter (it would be useful to give the definition of A_LT in terms of the R). For this reason could you also give/show the curves for R_L+R_TT+R_T? We have included two plots of R_LT and the cross section with our expected error bars. (See attachments 1 and 2.) 3. Why would initial state correlations have a predominant L character? Initial state correlations (ISC) would not be predominantly longitudinal, they will be both L and T. However, two nucleon currents (MEC and IC) will be predominantly transverse. If the relative proportions of ISC and two nucleon currents making up the cross section change, we will see it in A_LT more easily than in the cross section. 2. You talk about the 2N knock-out 'ridge'. What do you want to extract from that or learn? And one has to take into account the p_CM of the pair, which at the relatively low p_m values of the proposal may completely wipe out the 'ridge' character. We would like to learn whether the 2N KO 'ridge' exists at these kinematics. If it exists, there are calculations by Ryckebusch that most of the cross section comes from two nucleon currents (2NC), rather than from initial state correlations (ISC) (ie: the cross section including ISC only is much smaller than the cross section including ISC and 2NC). Measuring A_LT in this region will let us learn about the interplay of ISC and 2NC. In the p-shell, we are testing a well validated theory in an effort to find the limits of nucleonic descriptions of the nucleus. In the deep missing energy region on the other hand, we are exploring a previously unmeasured region, looking for new phenomena. 4. How sure are you that at higher p_m the 1/2+,5/2+ doublet cross section remains (relatively) small? The excitation mechanism of this doublet is probably more complicated than just direct k.o. We're not sure. In order to estimate the uncertainty we have calculated the effect on our results of including varying amounts of the 2s/1d from 0 to 100% (see attached figure [attachment 4]). We do have a measurement of the 2s/1d cross section at P_miss = 280 MeV/c from the previous part of the experiment. We will analyze that data to constrain the 2s/1d calculation. If the excitation mechanism is more complicated than just direct k.o., then I expect it is due to coupled channel effects driven primarily by the nearest state (the p3/2). If this is the case, then I expect that the ratio of the 2s/1d to the p3/2 would stay small. 5. You could gain (relevant) E_m coverage by using a central E_m > 20 MeV at the first setting. We could, but this would degrade the p-shell missing momentum acceptance. Since the omega acceptance is 50 MeV and the proton kinetic energy acceptance is 58 MeV, we have only a narrow missing energy region where the missing momentum acceptance is maximum. We have chosen to center this acceptance maximum on the p-shell. 6. What will be the real/random ratio in the continuum? Always greater than 1:1. See attached table (attachment 3). 7. What extra rate will you get from the e' acceptance outside your 50*50 cut? We will get a factor of approximately 5 in rate at the p-shell for measuring the cross section by increasing our omega-q acceptance. However, we would get at most 20-30% more matched rate for measuring R_LT. ----------------------------------------------------------- Lawrence Weinstein Associate Professor of Physics Old Dominion University Norfolk, VA 23529 757 683 5803 757 683 5809 (fax) weinstei@physics.odu.edu http://www.physics.odu.edu/~weinstei cumulus-stratus-nimbus (smoke signal)