[Hallb] Letter of Intent for the polarized EMC effect

Mark Strikman strikman at phys.psu.edu
Sat Dec 12 09:01:14 EST 2009

Dear Will,

A critique which influenced  evaluation of  the 6 GeV proposal was the  
issue of polarization of protons in 7Li as well as polarization of  
neutrons in 7Li. Really now that Jlab has established presence of the  
significant short-range tensor pn correlations in nuclei we definitely  
know that there exist significant corrections o the shell model  
estimates of polarizations.

When we did our calculations/analysis  with Vadim we were certainly  
concerned with this point. Hence we used the observation that g_1d <<  
g_1p to demonstrate that though the ratio g_17Li /g_1p is somewhat  
sensitive to uncertainties in the polarization of proton and neutron  
in 7Li, these effects do not change the x dependence of the ratio,  
while the polarized EMC effect does.

I think it would be important to emphasize that ability  of the  
experiment to study x dependence of g_1 in a wide range of x allows
to discriminate between the spin EMC effect and deviation of the  
nucleon  polarization of nucleons in 7Li from specific nucler models.

I think it would also nice to add an option of investigating using the  
same target (e,e'p) reaction with polarized 7Li as a method of
direct measurement of the spin structure of 7Li.

Best regards,


On Dec 11, 2009, at 3:47 PM, Will Brooks wrote:

> Dear CLAS collaborator,
>  Linked below is a draft letter of intent for CLAS12 that is planned  
> to
> be submitted to PAC 35 on Monday morning. It describes a measurement  
> of
> the "polarized EMC effect," that is, the modification of the g1 spin
> structure function of the proton within the nuclear medium. Your
> comments are solicited, and you are welcome to join the effort if you
> are interested.
> The document builds on the work from the 6 GeV letters of intent (V.
> Dharmawardane, LOI-06-003; A. Deur and X. Zheng, LOI-06-004) and
> benefits from an increased level of participation by theory experts  
> (A.
> W. Thomas, I. Cloet, W. Bentz, V. Guzey). Section 1 is expected to
> evolve somewhat further over the weekend.
> Best regards,
>  - Will
> http://www.jlab.org/~brooksw/LOI_12.pdf
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