Photodissociation dynamics of HO via the F̃ state at 111.5 nm were investigated using the high resolution H-atom Rydberg "tagging" time-of-flight (TOF) technique, in combination with the tunable vacuum ultraviolet free electron laser at the Dalian Coherent Light Source. The product translational energy distributions and angular distributions in both parallel and perpendicular directions were derived from the recorded TOF spectra. Based on these distributions, the quantum state distributions and angular anisotropy parameters of OH (X) and OH (A) products have been determined. For the OH (A) + H channel, highly rotationally excited OH (A) products have been observed. These products are ascribed to a fast direct dissociation on the B̃A state surface after multi-step internal conversions from the initial excited F̃ state to the B̃ state. While for the OH (X) + H channel, very highly rotationally excited OH (X) products with moderate vibrational excitation are revealed and attributed to the dissociation via a nonadiabatic pathway through the well-known two conical intersections between the B̃-state and the X̃-state surfaces.

In this study, the response of a Twin Frisch-grid ionization chamber (TFGIC) to fission fragments (FFs) was investigated using finite element and Monte Carlo methods. The entire process of the fission experiments, including FFs generation, gas ionization, electron drift and collection, and induced charge signal were well reproduced. Through data analysis, pulse height spectra from the anode and grid were transformed into energy and emission-angle information for the FFs. By means of double energy method, the pre-neutron emission fission fragment mass and total kinetic energy (TKE) can be finally determined. Experimental and calculated data of the mass and TKE distribution are shown in good agreement.

The electron beam dump for Dalian Advanced Light Source (DALS) is designed to absorb 15 kW of electron beam power at beam energy up to 120 MeV. The DALS accelerator produces an electron beam with very small beam size of up to 100 μA average current. The resulting beam power, up to 15 kW at 120 MeV, and the very high beam power density, pose challenging problems for beam dump design. High power dump with water cooled has been developed for DALS. In the dump, most of the beam power is finally absorbed in water and taken out from the dump. The core of the high power electron beam dump is designed to be constructed from an aluminum alloy using a cylindrical geometry with fins arranged around to promote the heat transfer. The cooling water is forced by a cooling pump, to cool the core of the dump through the cooling channels. The beam is stopped in the dump involving a high production of neutron and gamma radiation and activation of its surface. A shield has been designed to attenuate both the radiation produced during accelerator operation and the residual radiation. Design details for the dump, including radiation shielding calculations, thermal analysis are presented.

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