Yellow Report Physics Diffractive Reactions - Tagging

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Weekly Meetings

On Thursday 1PM Eastern Time


PWG Detector Matrix

Studies providing requirements on detector design

VM production

Contact: Spencer Klein, Sam Heppelmann

  • Wide coverage in eta up to pseudorapidity |eta|=5. Detection of 300 MeV pions from rho decay at these pseudorapidities ~+/-5 slides
  • Resolution requirement on separation of three Upsilon states slides. Handbook resolutions ok.
  • Phi production: Detection of 135 MeV Kaons at mid rapidity slides
  • Soft photons for nuclear breakup: Detection of photons with ~50 MeV for nuclear breakup (Far forward)slides, study in progress. Also order 50 MeV radiative decays in spectroscopy in the central region [needs detailed study, ballpark number for now]

Meson Structure

Contact: Tanja Horn Slides

  • ZDC:
    • 60cm x 60cm minimum, for K-Lambda need tracking and EMCal with high resolution/granularity in front of ZDC
    • EMCal: granularity for required physics angular or t-resolution: LG: 1cm x 1cm, HG: 100um x 100um
    • HCal: 10cm x 10cm (inner far forward) Resolution: 35%/√E (goal), <50%/√E (acceptable)*, 3mrad/√E (goal)
  • Hadron endcap calorimeter:
    • Good resolution for x-resolution (large-x processes): 35%/√E*. (* for large-x processes need delta x<0.1, where HCal resolution determines delta x. For a 50 GeV hadron/jet energy and 35%/√E, delta x=0.05)
  • Proton spectrometer:
    • B0: reduce beam pipe aperture to get most out of B0 sensors for pion measurement - need to find compromise between matching of apertures of different magnets. Rin~3.4cm, Rout~20cm, pixel pitch: 20-50umx20-50um, Zpos=5.9m, Xpos=15cm
    • Off-momentum sensor: working out the requirements on size to detect negative charge tracks. Pixel pitch: 500umx500um, Zpos=22.5m, Xpos=75cm
    • Roman Pots: Rin~10s, 20cmx10cm, pixel pitch: 500umx500um, Zpos=26.2m, Xpos=82cm (RP2: Zpos=28.2m, Xpos=91cm).

Deuteron Spectator Tagging (Diffractive and QE processes)

Contact: Z. "Kong" Tu and Alex Jentsch (Already communicated to DWG)

  • Neutrons:
    • Assume uniform acceptance for 0<θ<4.5 mrad
    • The real acceptance is a bit better than this, in reality, but the extra bit is not uniform in phi.
    • Resolution: Assume an overall energy resolution of σ_E/E=(50%)/√E ⨁ 5%. Assume angular resolution of σ_θ=(3 mrad)/√E
  • Protons:
    • Assume uniform acceptance for 6<θ<20 mrad – “B0 spectrometer”** For protons with p_z/(beam momentum)>.6 – “Roman pots”
    • 275 GeV: Assume uniform acceptance for .5<θ<5.0 mrad
    • 100 GeV: Assume uniform acceptance for .2<θ<5.0 mrad
    • 41 GeV: Assume uniform acceptance for 1.0<θ<4.5 mrad
    • For protons with .25<(p_z/beam momentum)<.6 -> off-momentum detectors
    • Assume uniform acceptance for 0.0<θ<2.0 mrad
    • for 2.0<θ<5.0 mrad, only accepted for |φ|>1 radian
  • Diffractive processes results have been submitted for publication in Phys. Lett. B

Elastic ep/ed scattering

Contact: Barak Schmookler

  • For elastic e-p scattering, the resolutions in the standard detector matrix are adequate to distinguish elastic events from DIS events. There are other non-DIS backgrounds that we haven't considered yet, which may require some study once a detector design is further along.
  • For elastic e-p scattering, if the central arm acceptance on the electron side extends to eta = -3.5, then the electron will enter the central acceptance at Q^2 below 1 GeV^2 (except for the highest sqrt(s) setting). Since the higher Q^2 measurements (say >10 GeV^2) are the most important here, an eta acceptance extending down to -3.25 (or -3 at worst, if we are prepared to lose some of the highest sqrt(s) data) is probably fine. Since it is best to detect the proton as well, far forward detectors are needed for the low Q2. It is better to have fewer gaps in the acceptance here between the far-forward and central acceptance regions. If the central acceptance can extend up to eta=+4, that would be best.
  • Kinematic plots or Slides 69-74 here
  • Elastic ed:
    • only generator level studies here
    • we can potentially make unpolarized measurements up to Q2~5 GeV^2 (slides 39-40), and tensor polarized asymmetry measurements up to Q2~2.5 GeV^2 (slides 49-51). The slides relevant to detector acceptance requirements are slides 22-26. Because only lower-Q2 measurements are possible here, it is preferable to extend the electron acceptance a bit more here (slide 24); eta down to -4 would be ideal to get very low Q2 for the tensor asymmetry measurements, but eta=-3.5 would allow measurements below Q2=1GeV^2, except for the highest sqrt(s).
    • best to detect deuteron as well

QE knockout (+SRC) on medium to heavy nuclei

Contact: Florian Hauenstein

  • Handbook detector values ok. There are some holes in acceptance which again can be complemented with a second IR. slides
  • Has been passed on to the far forward WG already.

3He with pp tagging

Contact: Dien Nguyen

  • The 3He(e,e’(pp_tagged))X results are extremely interesting as they show the biggest holes in the current design of the far forward region. While it is not our expectation that this will change the 1st IR’s far forward region, this result should be noted as very important for the 2nd IR far forward design as we would like to see areas that are missed by the first IR covered in the 2nd design.
  • Of particular note, is the low Pm (initial momenta of the nucleons relative the nucleus CM) tagged double protons. This would let us do a much more model independent F2n extraction then is currently done with 3He. This would be very similar to the BONUS type experiments done in Hall B (i.e. detecting the recoil protons from the deuteron to ensure that the neutron was onshell).
  • Alex Jentsch in the FF WG has the root trees from the 3He simulations as were provided by Dien, Jackson, Ivica, and Mark Baker making use of both a CLAS code as well as the BeAGLE Monte Carlo generator.

coherent 4He scattering

Contact: Mark Strikman

  • x_Pomeron < 0.01 (scattered 4He up to 99% beam momentum)
  • t-range from as small as possible (with good resolution) up to 0.6 GeV2; pT from 0 to 700 MeV. Slides
  • see also slide 2 here
  • Needs detailed studies

Inclusive diffraction

Contact: Wojtek Slominski

  • forthcoming (studies well underway, results expected within a week)

Diffractive Jets

  • Distinguishing diffractive jets from non-diffractive ones requires good charged and neutral coverage over the whole rapidity range with as few holes as possible.

Publications related to WG activity

  • M. Klasen, V. Guzey, Diffractive dijet photoproduction at the EIC, JHEP 05 (2020) 074, arXiv
  • Z. Tu, A. Jentsch, et al., Probing short-range correlations in the deuteron via incoherent diffractive J/ψ production with spectator tagging at the EIC, arXiv
  • W. Cosyn, C. Weiss, Polarized electron-deuteron deep-inelastic scattering with spectator nucleon tagging, arXiv


Elena Long (UNH) has made a plot template that emphasize low-angle regions and has a “visibility” option to highlight where tight kinematic bands are in something like elastic scattering. Top half are the normal linear scale, bottom half emphasizes the very forward and very backwards angles.

E and p visBar.png

Kinematic Coverage Files

Diffractive J/Psi production on deuteron with spectator tagging: eD -> J/psi +p'+n'

  • Contact: Kong Tu (BNL), Alex Jentsch (BNL)
  • Species: 10 GeV electrons on 110 GeV/A deuterons
  • Generator used: Beagle
  • Files (incl README) stored here (Contact W. Cosyn for password)
    • ROOT input file: eD_18X110_LFKine_Jpsi_New_1M.root
    • Script: eD_SRC_main.C. Produces output files, e.g., eD_18x110_*.root. One is for leading proton, and one is for leading neutron. All relevant plots are included in these files.
  • Comments:
    • Documented in paper
    • The forward-going nucleons are detected by proposed far-forward detectors, e.g., ZDC, Roman pot, Off-momentum detector, and B0 tracker. The acceptance and detector resolutions are simulated. The beam-related effects are also simulated.
    • These smeared distributions and ones with acceptance cuts are not included, only MC truth information is stored. The realistic GEANT simulations are done elsewhere, therefore not included here.

Initial momentum distributions

leading proton leading neutron
Figure 02 a.pdf
Figure 02 b.pdf

Elastic ep scattering

  • Contact: Barak Schmookler (Stony Brook), Elena Long (UNH)
  • Species: electrons on protons; 18x275, 10x100, 5x41, 5x100
  • Generator: self-written. See slide 5 here
  • Files stored:

electrons protons electrons and protons - log plot
E and p.png

Vector Meson Production

  • Contact: Sam Heppelmann (UC Davis), Spencer Klein (LBNL)
  • Species: ep (18x100), eAu (18x100)
  • Generator: eSTARlight
  • Files stored (includes README, script, root files): File:PhiPlots Sheppelmann.tar.gz
  • Slides
ep Q2 < 10 ep 0 < Q2 < 1 ep 1 < Q2 < 10
Phi K Q 10 0 ep 18 100.gif
Phi K Q 0 1 ep 18 100.gif
Phi K Q 1 10 ep 18 100.gif
eA Q2 < 10 eA 0 < Q2 < 1 eA 1 < Q2 < 10
Phi K Q 10 0 eA 18 100.gif
Phi K Q 0 1 eA 18 100.gif
Phi K Q 1 10 eA 18 100.gif

Sullivan Process (Meson Structure)

electrons meson
Scat e.png
Scat m.png
baryon baryon zoomed
Scat b.png
Scat b zoom.png

Quasi-elastic 2N knockout in eA

  • Contact: Florian Hauenstein (ODU)
  • Species
  • Generator: BeAGLE
  • Files stored:

Diffractive Dijets

  • Contact: Vadim Guzey (PNPI)
  • Theoretical study written down in arXiv:2004.06972 (V. Guzey and M. Klasen, JHEP 05 (2020) 074)
  • Archive with figures here File:Dijets, contains README, plots show dependence on pt, xγ_obs, xPom, zPom_obs, Δη
    ; a lot more figures included than shown below, see the paper linked above for a selection and more info.
  • Kinematic settings: e on p; 21 x 100, 18 x 275

zPom_obs xγ_obs
pt xPom

Yellow Report writing

  • Draft outline: Ch7 (physics),8 (study results) are were the bulk of our input should go.
  • Use inspirehep cite format for bibtex references!
  • Bibtex template for URLs, reports etc.

note = "\url{ }"

  • PWG asks for your contributions by October 15. This date is determined by the overall timeline for the YR. According to this timeline, a first complete draft of the YR must be ready about one week prior to the Berkeley meeting, i.e., around mid November. Also, coordinating edits within the physics part, and between the physics and detector parts of the documents is expected to take several weeks.
  • The expected total length for the sections in Chapter 7 (like 7.1) is 15-20 pages. This implies that the length of the subsections in Chapter 7 may vary from about 1 page to about 5 pages depending on the topic.
  • For Chapter 7, especially, we encourage a concise writing style. While we envision a coherent flow of the physics discussion, referring to previous EIC-related documents (such as the Whitepaper), review articles, and other original articles should be considered wherever useful and appropriate.
  • The discussion of new theoretical ideas should be very brief, if they are not accompanied by EIC-related impact studies. Please let us know if you think that an exception should be made for a particular topic.
  • The total of the detector requirements section of our WG (8.5) should not exceed 15 pages.
  • List of people and topics for chapter 7 "physics topics" + corresponding subchapter and their respective convener (please contact us to add names and topics!)
    • Inclusive diffraction (diffractive structure functions, diffractive pdfs) (Nestor Armesto, Paul Newman, Wojtek Slominski, Anna Stasto) [7.1.6 Inclusive diffraction (Anna Stasto)]
    • J/Psi inelastic diffractive production (Michal Deak,Anna Stasto, Mark Strikman) [7.3.2 Diffraction (Tuomas Lappi, Anna Stasto)]
    • Incoherent Photoproduction, and distinguishing coherent and incoherent production (Spencer Klein, Sam Heppelmann) [7.3.1 High parton densities and saturation (Tuomas Lappi, Bowen Xiao) 7.3.9 Coherent and incoherent photoproduction on heavy targets (Spencer Klein)]
    • Backward vector meson production (Spencer Klein) [7.4.5 New particle production mechanisms]
    • Exotica production (Spencer Klein) [7.4.4 Production mechanism for quarkonia and exotic states (Justin Stevens, Ivan Vitev)]
    • Nuclear (i.e. A>1) Gluonic Imaging (Kong Tu) [7.3.1 High parton densities and saturation (Tuomas Lappi, Bowen Xiao)]
    • Deuteron b1 Structure functions/tensor polarization (Elena Long, Christian Weiss, Wim Cosyn) [7.3.8 Structure of light nuclei (Or Hen, Wim Cosyn)]
    • Deuteron DIS with spectator tagging (Dmitry Romanov, Christian Weiss, Wim Cosyn) [7.3.8 Structure of light nuclei (Or Hen, Wim cosyn) 7.1.2 Spin structure of proton and neutron (Renee Fatemi, Nobuo Sato, Ralf Seidl, Daria Sokhan)]
    • SRCs from diffractive breakup (Kong Tu, Alex Jentsch, Florian Hauenstein, Jackson Pybus) [7.3.7 Short-range correlations, origin of nuclear force (Or Hen, Douglas Higinbotham)]
    • SRCs from tagged DIS (Jackson Pybus, Mark Baker) [7.3.7 Short-range correlations, origin of nuclear force (Or Hen, Douglas Higinbotham)]
    • SRCS from QE 2N knockout (Florian Hauenstein, Jackson Pybus) [7.3.7 Short-range correlations, origin of nuclear force (Or Hen, Douglas Higinbotham)]
    • 3He with pp tagging (Dien Nguyen, Ivica Friscic, Mark Baker, Jackson Pybus) [7.3.7 Structure of light nuclei (Or Hen, Wim Cosyn)]
    • 4He coherent scattering [Mark Strikman et al.] [7.3.4 Collective effects ]
    • Meson structure functions (Tanja Horn et al.) [7.1.3 Parton structure of mesons (Wim Cosyn)]
    • Diffractive jets (Michael Klasen) [7.3.2 diffraction (Tuomas Lappi, Anna Stasto)]
    • Inclusive jets (Vadim Guzey) [7.3.6 Special opportunities with jets and heavy quarks (Ivan Vitev)]
    • Elastic ep/ed scattering (Barak Schmookler, Elena Long, Andrew Puckett) [7.2.1 Form factors and 2D-imaging in position space (Douglas Higinbotham]