Experimental validation of a Tokamak neutron spectrometerbased on Bonner spheres * CAO Jing( ) 1,2;1) JIANG Chun-Yu( ) 1,2 CAO Hong-Rui( ) 1,2 YIN Ze-Jie( ) 1,2;2)

A search for heavy narrow resonances decaying into four-lepton final states has been performed using proton-proton collision data at √ s = 8 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 19.7 fb −1 . No excess of events over the standard model background expectation is observed. Upper limits for a benchmark model on the product of cross section and branching fraction for the production of these heavy narrow resonances are presented. The limit excludes leptophobic Z bosons with masses below 2.5 TeV within the benchmark model. This is the first result to constrain a leptophobic Z resonance in the four-lepton channel.

In order to make further studies on fusion neutron diagnosis on HL-2A /HL-2M, we have developed and succeeded in the calculation of the Response Function for a Bonner sphere spectrometer, which consists of eight polyethylene spheres with 3 He proportional counters inside. The response function of the Bonner spectrometer to neutrons is of fundamental importance for its neutron spectrum unfolding procedure and is directly related to the quality of the unfolded spectrum. In this paper, we calculated the response function to neutrons from 10 −9 MeV to 100 MeV by Geant4. In order to test the accuracy of the Geant4 simulation, we apply it to measure an 241 Am-Be neutron source, and the measured neutron counts of the spectrometer and simulated counts are found to be highly consistent, with a relative error up to 9.3%. This has proven the calculation of the neutron response of the Bonner sphere spectrometer by Geant4 to be quite accurate.

The Precision Proton Spectrometer (PPS) of the CMS and TOTEM experiments collected 107.7 fb-1 in proton-proton (pp) collisions at the LHC at 13 TeV (Run 2). This paper describes the key features of the PPS alignment and optics calibrations, the proton reconstruction procedure, as well as the detector efficiency and the performance of the PPS simulation. The reconstruction and simulation are validated using a sample of (semi)exclusive dilepton events. The performance of PPS has proven the feasibility of continuously operating a near-beam proton spectrometer at a high luminosity hadron collider.

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