[Clascomment] OPT-IN:Differential cross section and recoil polarization measurements for the gamma p --> K+ Lambda reaction using CLAS at Jefferson Lab

[Igor Strakovsky]

Dear Mike et al,

Paper looks outstanding but let me write my several comments for your consideration

* There are three general problems for me which are

- There is not much physics in (what new we may learn from your measurements)
[I strongly disagreed with the Paul\'s concern, intro comment is not enough for the good CLAS paper]

- Why you use non-standard frame to present differential cross sections. The standard is dSigma/dOmega, not dSigma/d\\cos\\theta as you do. Sure 2pi is very well known factor but you have to use a standard.

- Then, your paper has so many technical details. Your target is Phys Rev C not Nucl Instr and Methods. Try to ref Theses, CLAS Notes and so on. It will allow to focus.

* Abstract: Unfortunately, there is no physics in. No punch-line. What is the purpose of your measurements. You are saying about extra 300 MeV data - how it is critical to learn something new? Line 5: how good agreement is?

* pg 1, left, para 2: CLAS and SAPHIR have similar energy coverage. You may simplify your statement.

You may compare systematics of different experiments. I am sure that SAPHIR has an \'extraordinary\' systematics

* pg 1, right, para 2, last line: You may ref on the world data as Durham HEP or SAID databases, for instance.

* pg 1, right, para 3, line 8: Sorry, I cannot understand how possible to measure acceptance. Please clarify.

* pg 1, right, bottom: You use word \'these\' so many time. Please adjust

* pg 2, left, para 3: You use \'required\' several times

* pg 2, left, para 3, line 8: Ooops, \'The timing scintillators corresponding to low-energy photons...\'. Can you please help me to learn - how hardware may correspond to the particle?

* pg 3, left, para 3, line just after Eq(1): Oops, \'where \\vec p and \\beta are the momentum and velocity for the track...\'. Can you please help me to learn how track in the CLAS DC may have momentum and velocity? Or you are talking about a drift velocity?

* pg 3, left, para 3, line (hard to count): \'signal events\'. Please use an appropriate term

* pg 5, left, para 1, line 9: \'to the channel\' of what? Please clarify.

* pg 5, left, para 2, line 1: \'expansion of the data\' ?

* pg 5, left, para 2, line just after Eq(5): \'weighted accepted MC\' ??

* pg 5, left, para 2, next line: \'physically significant distributions\' ??

* pg 6, left, para 3, line 2: \'calculated\'==> \'determined\' ?

* pg 6, left, para 3, line 6: \'physics target\' ??

* Figs 4-6: I would give several plots (4 or 6) to illustrate this fact. You put a lot of figures which will give readers a hard time to focus. Same for Figs 10-12.

* Fig 7: I would skip it - too technical

That is all by now
Igor