SPIDER neutron diagnostic: Overall System Description

This document presents advances in the design of the CNESM neutron diagnostic for SPIDER. It is submitted as Progress Report P1.1 of subtask T3.5 of the F4E contract F4E-RFX-PMS_A-WP-2016. This is an update of the previous version, RFX_SPIDER_TN_169_r4, submitted as deliverable of the F4E contract F4E-RFX-PMS_A-WP-2015. This report describes the design of the CNESM diagnostic for SPIDER. The active part of the diagnostic is constituted by the nGEM detector whose design is fully described here together with all the services that are needed for its operation (gas system, HV system and DAQ system). The test of nGEM detector prototypes are described in report RFX_SPIDER_TN_170_r5. The report comprises the design of the detector box together with its integration with the beam dump and acceptance criteria (mainly concerning vacuum sealing), its installation/removal procedures and all the related services. The system design progressed in 2015 in the following areas: - Completion of the CNESM engineering design related to: - definition of the final detector position inside the SPIDER beam dump, - establishment of the final path of all the cables and pipes serving the diagnostic and choice of the tombak (after interaction with company) - Definition of the electrical scheme of the diagnostic - Study of the temperature variation of the detector box following heat exchange with the beam dump during SPIDER pulses In 2016 the design of vacuum chamber and pipe were finalised for procurement and the plan of on-site tests was revised. The main changes made in this version of the Report can be found in paragraph 2.1- 2.4 and 4. Risk management was also addressed. No major cause of concern could be foreseen.