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 - 20:26:04 EDT
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