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Measurement of particle ratios

in n-tagged events d+Au collisions at 200 GeV

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Aradhana Panday, Natasha Sharma, Lokesh Kumar

(IISER Berhampur, Panjab University)

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(In discussion with Zhangbu Xu and Prithwish Tribedy)

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n-tagged event selection in STAR

Analysis note: Phys. Rev. Lett. 128 (2022) 122303

• n−tagged data requires that a neutron be detected in the deuteron-going ZDC from deuteron breakup
• The ZDC n-tagged data is by placing an additional cut on the ZDC adc count on the deuteron going size
• An ADC cut greater than 40 is used in the analysis.

n-tagged event selection

n-tagged events

(cut at 9)

counts

System: d+Au 200 GeV (Run 16)

Library used: stardev

Trigger Id: 530003 (VPD-5)

Production: P17id

Files studied: picoDst

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Centrality Selection

Reference: I. Aggarwal (Quark Matter 2023)

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Momentum (GeV/c)

Momentum (GeV/c)

Counts

VertexY (cm)

VertexX (cm)

Mass² (GeV)²

dE/dx (keV/cm)

VertexZ(cm)

Track Cuts:

|y| ≤ 0.1

DCA < 3

ndedx ≥ 15 nHitsFit ≥ 25

Events and Track Selection

Event cuts:

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|Vz| ≤ 15

|Vr| ≤ 2

| Vz − Vpd | ≤ 3

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Events Analysed:

≅ 44 Million

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Raw Yield Extraction

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Transverse Momentum Spectra (Uncorrected) and Anti-proton to proton ratio (n-tagged/no tag)

50-100% centrality

For n-tagged events

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Transverse Momentum Spectra (Uncorrected) and Anti-proton to proton ratio (n-tagged/no tag)

0-100% centrality

For n-tagged events

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Proton double ratio comparison for 50-100% and 0-100% centralities

50-100%

0-100%

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Ongoing Work

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Working on anti-proton to proton ratios for n-tagged events and no-tag events at 60-100% and 60-80% centrality.