1 / 20

Using evaporated neutron number distribution as a saturation signature tagger

Using evaporated neutron number distribution as a saturation signature tagger. EIC taskforce meeting. A little bit recap. We found the correlation between number of forward neutron production and the traveling distance after collision in the nuclear.

more
Download Presentation

Using evaporated neutron number distribution as a saturation signature tagger

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Using evaporated neutron number distribution as a saturation signature tagger EIC taskforce meeting

  2. A little bit recap We found the correlation between number of forward neutron production and the traveling distance after collision in the nuclear. This correlation can be utilized to characterize eA collision geometry. By binning in produced forward neutron number, underlying traveling distance can be largely constrained.

  3. Neutron number handle constrains the collision geometries Counts 75-100% 50-75% 25-50% 0-25% Collisition geometry variable d has been effectively constrained by the neutron number handle from nuclei break up

  4. Neutron number distribution as a tagger for the saturation physics

  5. How does the nuclei break up in the saturated case? Nn ? Saturated: 1. Probe interacts coherentlywith all nucleons 2. No collision geometry sensitivity in z direction! Assumed to be the same as averaged configurations Fix geo config, impact b Averaged: iterations Sample interaction collect Nn All the following simulations based on evaporated neutrons from DPMJET + FLUKA for eAu collisions <Nn>

  6. The averaged (saturated) vs non averaged (non saturated) eAu 10 GeV x 100 GeV Averaged Non Averaged <Nn> <Nn> RMS shown as the error bar in every bin RMS shown as the error bar in every bin

  7. Kinematics dependence of neutron number distribution eAu 10 GeV x 100 GeV Shape of neutron number distribution does not depend on the kinematics Black: 10<Q2<20 Red: 1<Q2<2

  8. Significant difference between the sat/nosat break up neutron distribution eAu 10x100 Non Averaged eAu 10x100 Averaged 1<Q2<2 1<Q2<2 Red:Saturated Saturated case effectively cast into a mixture of the averaged and non averaged distribution. Difference from the nonsaturated distribution can be reckoned as the saturation signature. Red: from a 50-50 mixture of Averaged/Non Averaged distributions Solid: NonAveraged Dashed: Averaged

  9. Event generation process + + Nuclear remnant evaporation Intranuclear cascade Primary interaction Secondary interactions with the rest of the nucleon before flying outside h + N -> h(*)+ N(*) h = pi/K/p/n, N=p/n Need only mass, charge, excitation energy, no memory for prior history Pick 1 nucleon from initial geometry: e+p/n -> X+n All ep/en underlying processes are possible.

  10. Stages of neutron production + + Nuclear remnant evaporation Intranuclear cascade Primary interaction Evaporated neutrons fully accepted, contaminations under control. eAu 10 GeV x 100 GeV All final Cascade Evap ZDC cut

  11. Cascade neutron and geometry A correlation pattern observed in the intranuclear cascade neutron number and collision geometry. Intranuclear cascade Longer traveling distance More chance for secondary collisions

  12. Strategies to make the neutron number distribution: Measure neutron number distribution with ZDC in a wide kinematics range. In the nonsaturated regime, this measurement can be used as a handle for underlying collision geometry. In the saturated regime, we can compare the neutron number distribution with that from the nonsaturated region to find if saturation exists.

  13. Summary • Neutron number distribution from nucleus break up is sensitive to the underlying collision geometry. Possible applications in determining impact parameter for measurements like dihadron correlations and hadron attenuation. • In addition, we propose to utilize this measurement as a saturation tagger. Assuming the saturated forward neutron distribution can be simulated by averaged iterations, saturation phenomena can be significantly discriminated by scanning through the kinematics regime. • ZDC can be used to measure this neutron distribution efficiently with the systematics under control.

  14. Back up

  15. A handle to the eA collision geometry eAu 10 GeV x 100 GeV Counts Counts 75-100% 50-75% 25-50% 0-25%

  16. Sources of neutron production eAuEvap eAuNonEvap en ep Black: Evap+Cascade Red:Primary

  17. eAu 10 GeVx100 GeV 0.01<y<0.95 1<Q2<20 GeV2 Number of neutrons in pT FS (KS=1/-1) Evap (KS=-1) Cascade (KS=1) NoSec (KS=1) Two different mechanisms: Cascade neutrons (wide energy spectrum) Target remnant evaporation neutrons(narrow energy spectrum, mostly accepted by ZDC) Number of neutrons in eta Number of neutrons in E FS (KS=1/-1) Evap (KS=-1) Cascade (KS=1) E>80 (KS=1) FS (KS=1/-1) Evap (KS=-1) Cascade (KS=1)

  18. eCa 10 GeVx100 GeV 0.01<y<0.95 1<Q2<20 GeV2 Number of neutrons in pT FS (KS=1/-1) Evap (KS=-1) Cascade (KS=1) NoSec (KS=1) Two different mechanisms: Cascade neutrons (wide energy spectrum) Target remnant evaporation neutrons(narrow energy spectrum, mostly accepted by ZDC) Number of neutrons in eta Number of neutrons in E FS (KS=1/-1) Evap (KS=-1) Cascade (KS=1) E>80 (KS=1) FS (KS=1/-1) Evap (KS=-1) Cascade (KS=1)

  19. The two bump structures in Nn

  20. A depencence of neutron number distribution R = 1.12*A1/3+0.545*4.605 Red: <Nn> Black:NnRMS Pb Au Xe Cu Ca n Ca Cu Xe Au Pb Ca Cu Xe Au Pb

More Related