What about mid-rapidity. The referee is right, we are dealing with very geometric quantities and disregard our ability to change the geometry of the collisions. I was more afraid of man power problems. Ramiro On Aug 6, 2010, at 8:29 PM, flemming videbaek wrote: > I would think that getting centrality at high t will get difficult - at the present centrality we have 20-30 counts for deuterons, going to kess central we can likely only get ~10-14 counts at most. Protons is not an issue of course. > > Flemming > > Flemming Videbaek > videbaek @ bnl.gov > Brookhaven National Lab > Physics Department > Bldg 510D > Upton, NY 11973 > > phone: 631-344-4106 > cell : 631-681-1596 > > > > > > On Aug 6, 2010, at 8:22 PM, Ramiro Debbe wrote: > >> Great referee! (with Jamaican accent?) >> Can we get some centrality dependence? >> His comments about our physics arguments are sobering but we can certainly use his advice and improve our arguments. >> Ramiro >> On Aug 6, 2010, at 6:05 PM, flemming videbaek wrote: >> >>> Hi Michael, >>> I am going on vacation next week. I suggest you take the lead and >>> discuss it next Friday. JH will setup and lead that meeting >>> >>> Flemming >>> >>> >>> Flemming Videbaek >>> videbaek @ bnl.gov >>> Brookhaven National Lab >>> Physics Department >>> Bldg 510D >>> Upton, NY 11973 >>> >>> phone: 631-344-4106 >>> cell : 631-681-1596 >>> >>> >>> >>> >>> >>> On Aug 6, 2010, at 5:20 PM, Murray, Michael J wrote: >>> >>>> FYI >>>> >>>> >>>> Michael >>>> >>>> >>>> >>>> -----Original Message----- >>>> From: prc_at_aps.org [mailto:prc_at_aps.org] >>>> Sent: Fri 8/6/2010 12:48 PM >>>> To: Murray, Michael J >>>> Subject: Your_manuscript CS10219 Arsene >>>> >>>> Re: CS10219 >>>> Rapidity dependence of deuteron production in Au+Au collisions at >>>> sqrt s NN=200 GeV >>>> by I. Arsene, I. G. Bearden, D. Beavis, et al. >>>> >>>> Dear Dr. Murray, >>>> >>>> The above manuscript has been reviewed by one of our referees. >>>> Comments >>>> from the report appear below. >>>> >>>> These comments suggest that specific revisions of your manuscript are >>>> in order. When you resubmit your manuscript, please include a summary >>>> of the changes made and a succinct response to all recommendations or >>>> criticisms contained in the report. >>>> >>>> Yours sincerely, >>>> >>>> Bradley Rubin >>>> Senior Assistant Editor >>>> Physical Review C >>>> Email: prc_at_ridge.aps.org >>>> Fax: 631-591-4141 >>>> http://prc.aps.org/ >>>> >>>> Physics - spotlighting exceptional research: http://physics.aps.org/ >>>> >>>> PROBLEMS WITH MANUSCRIPT: >>>> >>>> In reviewing the figures of your paper, we note that the following >>>> changes would be needed in order for your figures to conform to the >>>> style of the Physical Review. Please check all figures for the >>>> following problems and make appropriate changes in the text of the >>>> paper itself wherever needed for consistency. >>>> >>>> Figure(s) [4] >>>> Please rearrange power of 10 in axis label for clarity: >>>> Either >>>> (i) place the power of 10 as a factor, without parentheses, >>>> in front of the axis label quantity, changing the sign of the >>>> power as needed; or (ii) incorporate the power of 10 in the >>>> topmost or rightmost number on the scale. Please refer to >>>> the URL http://forms.aps.org/author/h18graphaxislbls.pdf >>>> for a >>>> pictorial representation of the preferred forms for axis >>>> labels. >>>> >>>> Figure(s) [please check all and amend where necessary] >>>> The lettering in the axis labels and/or numbering size >>>> should be >>>> increased. Please ensure that all lettering is 2 mm or larger >>>> (1.5 mm for superscripts and subscripts) after scaling to the >>>> final publication size. Note that the column width is 8.6 cm >>>> (twice that amount plus gutter for extra wide figures). >>>> >>>> >>>> Please remove the redundant arXiv references for published papers. >>>> For your information, the editorial office checks the references at >>>> several crucial steps during the editorial process. A list of >>>> unnecessary >>>> arXiv references slows the process down considerably--particularly so, >>>> if the list is long--and delays the processing of your manuscript. >>>> >>>> Please note that the copy editors will remove such redundant links >>>> during >>>> production for those papers that have been accepted for publication. >>>> However, any manual intervention carries the risk of inadvertently >>>> introducing mistakes. >>>> >>>> ---------------------------------------------------------------------- >>>> Report of the Referee -- CS10219/Arsene >>>> ---------------------------------------------------------------------- >>>> >>>> Executive Summary: >>>> ----------------------------------------- >>>> The paper is a straightforward, almost minimalist, presentation >>>> of a data set on proton and deuteron production in central Au+Au >>>> RHIC collisions over a wide range of rapidity, and antiproton and >>>> antideuteron production over a smaller range in rapidity. The >>>> data are interpreted in terms of a standard coalescence picture >>>> and an extracted phase space density; some trends are noted but >>>> no definite physics conclusions are drawn. As a simple data >>>> presentation exercise the paper is generally acceptable, though >>>> the physics impact of the data are significantly limited by >>>> being restricted to only central collisions in only one bin of >>>> centrality. >>>> >>>> Though I would not suggest it as a requirement for publication >>>> in the Physical Review, I would urge the authors to consider >>>> enlarging the paper to include data from a greater range of >>>> centrality classes -- based on the error bars shown in Fig 5 >>>> it certainly looks as though sufficient statistics would be >>>> available. >>>> >>>> Modulo that decision, the paper has a number of minor errors >>>> in the physics introduction which should be addressed, as >>>> detailed below. My basic recommendation, then, is that the >>>> paper will be suitable for publication with minor corrections. >>>> >>>> >>>> Concerns: >>>> -------------------------------------- >>>> (1) Centrality selection. The data presented in Fig 3 are for some >>>> particular event selection; but which? One needs to scan the >>>> paper in some detail (or use a computer text search) to find >>>> the lone sentence "We present ... AuAu collisions with a centrality >>>> range of 0-20%." in the first paragraph under Section II. Analysis. >>>> (Note that this sentence itself is not quite grammatically correct.) >>>> >>>> Physics: Why was this one, and only one, centrality range chosen >>>> for this analysis? There is no motivation mentioned in the paper >>>> at all, which is quite puzzling. The paper describes interpretation >>>> in terms of geometrical quantities such as the coherence volume >>>> implied >>>> by the B_2 measurement; it is only natural to ask, then, how these >>>> might change as the collision geometry/centrality is changed. To >>>> present data from only one centrality selection, with no explanation, >>>> seems quite odd and un-natural, and I would call it a glaring defect. >>>> There is of course a limit on available particle statistics, but it >>>> is far from clear (partly because there is so little detail provided >>>> on the error analysis) that no statement could be made for any other >>>> selections, even by breaking the current one into two. >>>> >>>> Analysis: The section on the data analysis should include a >>>> description >>>> of how the events were selected on centrality. >>>> >>>> Formatting: Assuming that the paper is to be published on just the >>>> central collision results, that fact should be made clear throughout >>>> the work: it should appear in the title, in the abstract, in the >>>> summary and in the captions of all the figures and tables. And, >>>> for that matter, the main data graphs such as Fig 3 should also >>>> state that these results are for the Au+Au collision system! >>>> >>>> >>>> (2) Error analysis. The presentation in Table I does a good basic job >>>> of explaining the uncertainties: statistical errors are in the table, >>>> systematics are characterized in the text. All of the figures and >>>> tables should rise to this same standard: what is shown by the errors >>>> that are displayed? and what are the sizes of the other sources? >>>> >>>> Elsewhere the treatment of uncertainties is uneven. The discussion >>>> of errors from the feed-down correction in Section II.D is quite >>>> quantitative; while the preceding section II.C on particle >>>> identification describes inefficiencies and contaminations, but does >>>> not quote anything quantitative for the residual uncertainties from >>>> these effects. At a minimum the reader should be able to appreciate >>>> the relative contributions of statistical versus systematic >>>> uncertainties, and what the dominant source is for the systematic, >>>> for every quantity quoted and plotted in the paper. >>>> >>>> >>>> (3) Abstract: "in contrast to lower energy data". This should be >>>> re-worded to make clear that it refers to data from collisions >>>> at lower collision energies, rather than lower secondary particle >>>> energies. >>>> >>>> (4) p1 col2: "surrounding ... medium ensure energy and momentum >>>> conservation". "Ensure" would be better as "allow" or "permit" >>>> or "enable". Conservation laws always "ensure" that they are >>>> followed; the role of the medium is to "allow" p + n -> d >>>> to proceed without the need to emit a photon. >>>> >>>> >>>> (5) p1 col2 "As deuterons are formed inside the expanding system" >>>> Is this really true? How do you know? One could make the simple >>>> argument that particle within the medium are colliding often >>>> enough, on the order of once per ~1-10 fm/c or faster in the time >>>> before freezeout, then the constituent protons and neutrons will >>>> on average be off their mass shell by ~200-20 MeV at any given >>>> moment; if this is true, then how can one even distinguish a >>>> deuteron bound state, whose binding energy is only 2 MeV? >>>> The bound/unbound distinction doesn't apply over such short >>>> time scales. >>>> The same misconception appears later in the same paragraph >>>> with the phrase "deuterons are most likely formed very near >>>> freeze-out". What, exactly, does "formed" mean here? In order >>>> for a p,n pair to be meaningfully distinguished as either bound >>>> or unbound, the degree to which they are off-mass-shell must be >>>> no larger than the bound-state binding energy. This implies that >>>> bound-state deuterons cannot even be _defined_ until ~100 fm/c >>>> have passed since the particles' last momentum transfer >>>> interaction, ie freezeout; this time frame cannot be described >>>> as "very near freezeout." It really makes no sense to say that >>>> deuterons are "formed" on a timescale faster than they can even >>>> be distinguished or defined, whether inside the colliding system >>>> or following freezeout, so this whole passage of the >>>> introduction is really misconceived. >>>> The reason that sudden-approximation coalescence models can >>>> work is more subtle, quantum mechanically. After the last >>>> momentum exchanges, ie freezeout, all the protons and neutrons >>>> will be in wavefunctions which span a range of masses around >>>> their free-particle on-shell rest mass. The off-shell >>>> combinations of momentum and energy will decay away with time, >>>> ie the amplitude of those parts of the wavefunctions will >>>> diminish and only the on-shell states will have significant >>>> amplitudes. So, looking into the future at the time of >>>> freezeout it is reasonable to count only the on-shell states >>>> for future accounting purposes; but the off-shell states are >>>> still present in the wavefunction at that time. >>>> For this reason, one can get reasonable answers from a >>>> coalescence model while neglecting these off-shell subtleties. >>>> But, by the same token, there is no excuse at this point in >>>> the field for leaving a sloppy definition of "formed" in the >>>> introduction to a paper like this, and the section should be >>>> rewritten without this misconception. >>>> >>>> >>>> (6) p1 col2: "Coalescence models assume that the distribution >>>> of clusters..."; "density" or "phase-space density" would be >>>> better than "distribution" >>>> >>>> >>>> (7) p1 col2 and Eq. 1: The references [1-3] quoted to >>>> introduce the notation of the coalescence picture in Eq. 1 >>>> are incomplete; they date from the Bevelac era (or earlier), >>>> when the notation C_2 was used for the proportionality >>>> similar to that in Eq. 1 but with cross sections rather than >>>> per-event densities. The B_2 notation used here was originated >>>> during the AGS fixed-target heavy-ion program, starting with >>>> E858 and then E864 and E878; and it is a rather glaring >>>> omission that not all of these experiments are referenced in >>>> this paper, which should be corrected. >>>> >>>> >>>> (8) p1 col2: Mention is made of the n/p ratio in lower-energy >>>> collision data, but the meaning and significance are not clear >>>> at all. What system was this for? Does this n/p ratio >>>> correspond to that of the incoming nuclei, or not? Is the >>>> implication that Eq. 1 should be modified, or assigned a 20% >>>> systematic error? If not, why not? The bare inclusion of >>>> this observation, without any details, explanation or >>>> implication is simply confusing and not helpful to the reader. >>>> >>>> >>>> (9) p2 col1: "B_2 carries information about the cluster" >>>> What do you mean by "cluster"? Is it the deuteron itself, as >>>> implied on the previous page with the phrase "the distribution >>>> of clusters"? Or does "cluster" mean the system as a whole? >>>> Neither really makes sense; B_2 doesn't really tell you >>>> anything about the deuteron itself per se; and it's strange, >>>> as well as inconsistent with the previous page, to refer to >>>> refer to the whole system as a "cluster". >>>> >>>> (10) p2 col1: "B_2 ... is consistent with measurements of >>>> the deuteron wave-function." This is a very strange and >>>> jarring statement to read at this point in the paper, since >>>> there has been no discussion up to this point on how the >>>> deuteron's spatial properties figure into the value of B_2 >>>> through the coalescence process or otherwise. >>>> >>>> (11) Also, this statement is referenced to Ref 5, but only >>>> vague mention is made of what collision systems or what >>>> collision energies are being referred to; this makes it >>>> somewhat strange to read in the very next sentence that >>>>> = 4.9 GeV is the threshold of "high energy". It would >>>> be clearer to state the energy ranges, and at least whether >>>> heavy or light nuclei are involved, for all the data being >>>> referred to (this remark applies in several other places >>>> throughout the current paper, as already mentioned in >>>> point 8 above). >>>> >>>> (12) p2 col1: "assuming the region where the coalescence >>>> occurs has also a Gaussian shape" See point 5 above; the >>>> region which sources/radiates the nucleons is not the same >>>> thing as the region where coalescence occurs. Note also >>>> that "spatial profile" would be better than "shape" in >>>> this sentence. >>>> >>>> (13) p2 col1: "this ansatz ... facilitates comparison to >>>> interferometry radii". A traditional point; but, how does >>>> the comparison work in this case? First, should the R_G >>>> from the coalescence framework analysis be compared >>>> directly to any of the R parameters from HBT analysis? >>>> or is there a factor of 2, or pi, etc between them? >>>> Is this paper going to actually make the comparison? >>>> if not, then you should provide a reference to how the >>>> comparison should be done. >>>> >>>> (14) p2 col1: "However, it has been suggested that..." >>>> This certainly needs a reference, or several, at this point. >>>> >>>> (15) p2 col1: The middle paragraph discusses the results >>>> of deuteron production following a quark coalescence picture, >>>> which is a subject of considerable current interest. However, >>>> the logic is not laid out clearly here. Isn't it true, for >>>> example, that if protons follow the quark coalescence picture >>>> and deuterons follow the nucleon coalescence picture, then >>>> deuterons automatically/necessarily follow quark coalescence >>>> as well? ie isn't quark coalescence for deuterons redundant >>>> with nucleon coalescence? and so not really an independent >>>> piece of information. Alternatively, is the statement that >>>> deuterons follow quark coalescence equivalent to B_2 being >>>> constant with pT? But here B_2 is not constant with pT, as >>>> we see in Fig 4; doesn't that have immediate implications for >>>> quark coalescence interpretation of the present data? >>>> In general this section should be written so as to make >>>> it clear to the reader what are, and are not, redundant versus >>>> independent pieces of information. >>>> >>>> (16) p2 col1: The start of the discussion of discussion of >>>> phase-space densities in the last paragraph should have at >>>> least a few references right at the beginning, especially >>>> as to the motivations. Why is this an interesting quantity? >>>> The text mentions (i) an indicator or measure of the degree >>>> of equilibrium, which is directly connected to entropy, >>>> and (ii) "information about ... symmetrization efects". >>>> Reasonable enough; but what's the upshot? What do the results >>>> shown in Fig 5 demonstrate? Trends are noted in Section III, >>>> but what about the basic magnitude of the measured quantity? >>>> is it high, is it low? >>>> >>>> (17) p2 col2: The result of Eq. 5 is correct only for a true >>>> global equilibrium, with one universal temperature and where >>>> the particles have equal access to the entire relevant volume. >>>> The text acknowledges this, but only in a roundabout way with >>>> the later remark "we are ignoring the collective motion of the >>>> particles", as collective motion is a departure from true >>>> global equilibrium (also, "neglecting the possibility of" is >>>> more accurate than "ignoring" here). But since collective >>>> motion probably is the case in RHIC Au+Au collisions, from the >>>> B_2 results shown here as well as a host of other evidence, >>>> it is left unclear to what extent Eq.'s 5 - 9 should still be >>>> considered relevant. For example, in the statement farther down, >>>> attributed to Ref 23, that strong longitudinal flow could >>>> significantly reduce pion phase space densities, it is not clear >>>> if this is a true result about the actual density or an artifact >>>> of Eq. 5 and its corollaries being invalid in the extraction of >>>> the measured phase-space density. >>>> In general the utility of a framework which assumes global >>>> equilibrium to a system which probably exhibits only local >>>> equilibrium needs to be explained more carefully; if T is a >>>> function of space, then is Eq. 5 still true at a point? In >>>> the case of collective motion being significant, is Eq. 3 >>>> defined over some relevant coherence volume? etc. >>>> >>>> (18) p2 col2: "the maximum space averaged phase-space density, >>>> which is at the center of the Gaussian source." Sorry, but >>>> this makes no sense at al: a spatial average is not defined >>>> for different points within the space. The confusion over >>>> the relevant spatial volumes mentioned in point 17 above >>>> is clearly causing serious trouble here. >>>> >>>> (19) p2 col2: In Eq. 9, is R_G a function of particle >>>> momentum, particularly pT? Presumably so, and if so then it >>>> would be useful to write the dependence explicitly here. >>>> >>>> (20) Minor formatting: the text following Eq. 5 should >>>> probably be left-justified rather than indented. It is not >>>> clear whether the text following Eq.'s 4 and 6 should or >>>> should not start new paragraphs, either. >>>> >>>> (21) The presentation of Eq. 6 in terms of chemical potential >>>> is formally correct, but at the same time obscure -- in the >>>> dilute limit, what is the value of these chemical potentials? >>>> Is it just the particle mass, which would make Eq. (6) >>>> equivalent to exp[-mT/T] at all rapidities? or does it vary >>>> significantly with the net baryon density, which changes >>>> considerably with rapidity (as BRAHMS has made clear in >>>> other measurements)? >>>> >>>> (22) p5 col2: "expect the ratio of the proton and antiproton >>>> phase densities to be flat"; is this as a function of >>>> rapidity? or pT? or both? >>>> >>>> (23) Summary, but also relevant to several sections of the >>>> paper: There is a reasonable interpretation here that the >>>> B_2 and phase space density measurements have information >>>> about the existence of collective flow, particularly what >>>> is called radial flow. This is certainly valuable and >>>> worth publishing. However, the current paper doesn't say >>>> much about whether these implications are or are not >>>> consistent with the great body of work that has now been >>>> done on modeling RHIC A+A collisions with hydrodynamics. >>>> It is not necessarily the responsibility of this paper >>>> to make a full-blown analysis, but the reader deserves some >>>> basic orientation: are the results shown here generally >>>> consistent with existing hydrodynamical models? or is >>>> there some kind of surprise or contradiction brewing? >>>> >>>> >>>> _______________________________________________ >>>> Brahms-dev-l mailing list >>>> Brahms-dev-l_at_lists.bnl.gov >>>> https://lists.bnl.gov/mailman/listinfo/brahms-dev-l >>> >>> _______________________________________________ >>> Brahms-dev-l mailing list >>> Brahms-dev-l_at_lists.bnl.gov >>> https://lists.bnl.gov/mailman/listinfo/brahms-dev-l >> _______________________________________________ Brahms-dev-l mailing list Brahms-dev-l_at_lists.bnl.gov https://lists.bnl.gov/mailman/listinfo/brahms-dev-lReceived on Fri Aug 06 2010 - 20:36:24 EDT
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