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Hi,</div>
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I am attaching a draft of the abstract for the upcoming workshop. Please let me know if you have any</div>
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comments/suggestions.</div>
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Thanks,</div>
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Sasha</div>
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The Jefferson Lab Eta Factory Experiment and Applications of PbWO₄ Calorimeters in Future </div>
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Experimental Facilities</div>
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The goal of the new JLab Eta Factory (JEF) experiment, conducted with the GlueX detector in Hall D at </div>
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Jefferson Lab, is to perform measurements of various $\eta^{(\prime′)}$ decays with a primary focus </div>
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on rare neutral modes. The experiment's physics program ranges from precision tests of low-energy QCD </div>
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to searches for gauge bosons with masses below 1 GeV that could couple the Standard Model (SM) sector </div>
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to the dark sector. The experiment will collect a high-statistics data sample of $\eta^{(\prime′)}$ mesons </div>
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produced via a beam of tagged photons. The GlueX detector features a large, nearly uniform acceptance for </div>
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both neutral and charged particles, enabling efficient identification of complex multi-particle final states.</div>
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To meet the requirements of the JEF experiment, the inner section of the forward lead-glass calorimeter in the </div>
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GlueX detector has been upgraded with lead tungstate (PbWO$_4$) scintillating crystals. PbWO$_4$ offers exceptional </div>
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characteristics, such as a small radiation length and Molière radius, and large light yield, that make it ideal </div>
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for constructing high-granularity, high-resolution, radiation-hard detectors. These properties enable excellent </div>
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spatial separation and energy resolution of reconstructed electromagnetic showers, establishing PbWO$_4$ as the </div>
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material of choice for many high-precision experiments. The JEF experiment began data collection in April 2025 and </div>
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will operate concurrently with the GlueX experiment, whose primary objective is the search for gluonic excitations </div>
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in the meson spectrum. I will give an overview of the JEF experiment, the GlueX detector, and the feasibility of further </div>
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upgrades to support future $\eta$ physics studies. Special attention will be given to the newly constructed PbWO$_4$ </div>
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scintillating calorimeter and recent advancements in calorimeter instrumentation.</div>
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