<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-family: Calibri, sans-serif; "><div><div><div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">Dear Collaborators,</span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "> As Andrew briefly discussed last Wednesday at the SBS weekly phone meeting.</span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "> Andrew, Nilanga and myself have been developing a proposal to PAC42 on measuring SIDIS beam-target double-spin asymmetries on a longitudinally polarized 3He target (A_1n^h on neutron), for nucleon spin-flavor decomposition, with the SBS+BB combination. The key features of the experiments are:</span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "> 1. High luminosity, high polarization, pin down A_1n^h extremely well on a dense grid of (x, Q2, z) and vs hadron p_t. The precision data set will feed into DSSV NLO QCD global fit, which will include DIS, SIDIS as well as inclusive pi^0, jet, and W boson asymmetries from RHIC p+p. The high precision data set will put tight constraints on valence quark polarization, sea quark polarization, and indirectly on gluon polarization.</span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "> 2. Accessing polarized neutron information, have a much better F.O.M compared to CLAS12 with ND3, NH3 combination.</span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">BigBiet at 30 degree as electron arm, to reach the highest possible Q^2 coverage for SIDIS at JLab12 GeV, complementary to SoLID's kinematic coverage. </span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "> 3. Well controlled hadron particle identification, by RICH, for a clear pion/Kaon separation. Straight-line tracking in the detector package.</span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "> 4. Identical phase space for positive and negatively charged pion, so that we can pin down A_{1He}^{\pi^+ - \pi^-} very well. This flavor non-singlet observable is of special interest, gluon density, gluon polarization, and gluon fragmentation functions drop out to all orders in QCD. Under the assumption of SU(2) symmetry, only valence quark's polarization contributes to this special asymmetry combination, sea quarks drops out. Thus, a better way to achieve spin-flavor decomposition, without requiring detailed knowledge of quark to pion fragmentation functions. </span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "> 5. On a polarized neutron (3He) target, we are more sensitive to \Delta d, \Delta dbar. In addition to access valence quark polarization, we can also access sea quark polarization, \Delta ubar, \Delta dbar, and polarized sea flavor asymmetry (\Delta ubar - \Delta dbar). Recent STAR W asymmetry data strongly favors a positive sea up-quark polarization at x=0.05-0.2. A precision measurement in SIDIS reaction is very urgently needed to verify the apparent positive ubar polarization, and to provide the first information on dbar polarization. The results will strongly impact EIC's physics program.</span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "> 6. We can pin down valence quark polarization very well, from x=~0.15 to x=~0.7. This is one of the major physics program that drove the Jlab-12 GeV upgrade.</span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "> 7. Experimental set up is very similar to that of SBS+BB Transversity, with longitudinally polarized 3He target, can fit into the same run group.</span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "> 8. SIDIS multiplicities will also be measured in the same setup, using reference cells.</span></div><div style="font-family: Arial; font-size: medium; "><font class="Apple-style-span" face="Calibri"><br></font></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "> we have a working draft of a proposal for pac42 (deadline June 2nd), please take a look at:</span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><br></span></div><div style="font-family: Arial; font-size: medium; "><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Calibri; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span style="font-family: Calibri; font-size: medium; "> <a href="https://userweb.jlab.org/~puckett/PAC42_deltad/main_Deltaq.pdf">https://userweb.jlab.org/~puckett/PAC42_deltad/main_Deltaq.pdf</a></span></span></div><div style="font-family: Arial; font-size: medium; "> <br></div><div style="font-family: Arial; font-size: medium; ">Several plots and sections are still under construction, references are not all fixed yet.</div><div style="font-family: Arial; font-size: medium; "><br></div><div style="font-family: Arial; font-size: medium; ">We very much appreciate your supports. Please consider to join this proposal. </div><div style="font-family: Arial; font-size: medium; ">Please email us a list of collaborators from your institution.</div><div style="font-family: Arial; font-size: medium; "><br></div><div style="font-family: Arial; font-size: medium; "> Thank you very much,</div><div style="font-family: Arial; font-size: medium; "><div><br></div><div>Andrew, Nilanga and Xiaodong</div></div></div><div><div><div><div><br></div><div>------------------------------------------------------------------------------</div><div> Xiaodong Jiang</div><div> P25 group, MS H846, Tel. 505 606 0437</div><div> Los Alamos National Laboratory</div><div> Los Alamos, NM 87545</div><div>------------------------------------------------------------------------------</div></div><div><br></div><div><br></div></div></div></div></div></body></html>