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Towards a forward dN/deta paper

Updated on Sat, 2021-01-16 15:20. Originally created by lisa on 2020-04-15 13:53.
Intention: publish dN/deta in the region 2<|eta|<5 for several collision energies from STAR BES.

Proposed datasets

Table 1: Datasets proposed for inclusion in the paper
system year taken dataset production #events (M) comments  beam rapidity (lab frame) For nominal Vz (0 for collider, 200 for FXT) what ring is beam rapidity?  (See figure 3) Range of eta-prime=eta-ybeam (see fig 2) that we can reach, by varying Vz reasonably
Au+Au 3.0 GeV FXT 2018   P19ie 351 production finalized.  But centrality not yet finalized -- At BulkCorr 15 April, Daniel promised an update at Bulkcorr "next Wednesday"  2.1 (note FXT, so beam at 3.28 GeV in lab and target around z=2 m) (way) outside row 16, in TPC region [+0.45,+3.4]  pretty much useless
Au+Au 7.7 GeV (collider) 2019   P19ic 0.7 not an official production???  EPD not calibrated :-(  2.1 at outer edge of 16 [-0.2,+3.3]  almost no range on neg side
if we go to Vz=200, then [-0.7,+3.3]
 
Au+Au 14.6 GeV 2019   P19ic 13 EPD definitely not calibrated :-(  2.74 9 [-0.84,+2.66]  less than one unit on negative side
Au+Au 19.6 GeV 2019 ??   -   crucial to compare to PHOBOS!!! 
  • In September 2019, we heard "two weeks" (c.f. Joey slide)
  • At LFS meeting 13 April 2020, Grigory promised "next week"
  • At LFS meeting 27 April 2020, Daniel promised "in two weeks"
  • At the same 27 April meeting, Irakli said I could have 1M events in picos from a non-final production "soon"
  • ... and so on...
  • At the January 2021 online analysis meeting, Lijuan said two weeks or two months.
  3.03 7 [-1.13,+2.37]
Au+Au 27 GeV 2018 27GeV_production_2018 P19ib 1700 Finalized, I think.  3.36 5 [-1.46,+2.04]
Au+Au 54 GeV 2017    P18ic 1700 Only 1/8 of EPD was installed, but should be plenty.  4.05 2 or 3 [-2.15,+1.45]

Information on this came from www.star.bnl.gov/public/comp/prod/DataSummary.html

Note that these energies make a nice "rough doubling" of energies.  And when you add in PHOBOS 130 and 200 GeV results, we go from 3.85 GeV to 200 GeV in six steps of (approximately) a factor of 2.  This is roughly six octaves.  Or, another way to look at it....


Figure 1.  Energy "scales."   The collision energies, sqrt(sNN), in GeV, are spread relatively evenly over 6 octaves, displayed on a piano keyboard.  STAR will study the green keys, and PHOBOS did the red.  An exception to the even spacing is the datapoint at 19.6 GeV, right at "middle C," which provides a crucial touchstone between PHOBOS and STAR, right in the middle of the range.


So when we "fill in the gaps and extend,"  how will this plot look like?  When does it break down?


Figure 2:  Figure 2 from the PHOBOS 2002 paper which can be found here.


As I've discussed before, the coverage of an EPD wheel depends on the primary vertex position.  Below is a handy plot of rings of the West EPD as a function of primary vertex. 
  • Beam rapidity for 14.6, 19.6 and 27 GeV is nicely covered by several small (in delta-eta) rings if we stay to say |Vz|<75 cm (grey vertical lines). 
  • For the 54 GeV data, we will always have beam rapidity in rings 2 or 3; we could have it in ring 1 if we use Vz~150 cm or in ring 4 if we use Vz~-150 cm.
  • For the 7.7 GeV data, we will need to go out to about 100 cm, which is fine actually.  Who cares if the TPC acceptance gets very narrow?
  • The position of the fixed target is at Vz=200 cm, and one measures eta<0 (East EPD).  Since I made this picture for West EPD (eta>0), I put the fixed target at -200 cm, to make the equivalent plot.  The plot shows us that with the primary vertex there, we will cover down to 2.55, so we do not have coverage of the beam rapidity of 2.1 in our acceptance.  I'm not entire sure what this means for our paper.  Maybe this energy is therefore useless?  We should discuss.


Figure 3 Coverage each ring of the West EPD wheel, as a function of primary vertex position.  The location of the fixed target holder is shown (Actually, the holder is at +200 and we use the East wheel and negative eta.  Since this picture is for the West wheel, use vz=-200 and flip all signs appropriately.).  Also shown are the beam rapidities of the data that we'd like to include in this paper.  Click here for the macro used to make this plot.


Starting at this point is just some stuff for me...


For my own sanity, some pages that show production status and datasets:


Finding/getting the picoDsts....


So I don't have to keep asking Joey over and over, here is how to find picoDsts:
  • "get_file_list.pl -keys path,filename -delim '/' -condfiletype=daq_reco_picoDst,trgsetupname=27GeV_production_2018,tpx=1,filename~st_physics,sanity=1,production=P19ib -limit 0"
    will list all of the picoDsts for that production,
  • you can specify a range of run numbers with e.g. "...,sanity=1,runnumber[]19161003-19161010 -limit 0" or just change the number of listed files with the "-limit".
Often, you will find these picoDsts already on disk!  If not, if they are on HPSS, you can export the result of the above command into a list:
  •  "get_file_list.pl .... > RunsToRestore.list"
  • "hpss_user.pl -r [Restore directory] -f RunsToRestore.list"
  • Check the status at https://www.star.bnl.gov/devcgi/display_accnt.cgi; it may take anywhere between half an hour and a day. Usually it doesn't take long, but people have been having file access issues lately so maybe it will fail. A lot of times, when I check the status at that link, I will get an error message along the lines of "non-recoverable error occurred", followed by a successful restoration a while later... strange.
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