Frank Lopez, Hans Herrmann, Ramon Leeper, Steve Batha, John Oertel, Jeffrey Griego, Brian Steinfeld, Paul Polk, Lynne Goodwin, Valerie Fatherley, Thomas Archuleta, Robert Aragonez, Benjamin Pederson, John Celeste, Robin Hibbard, Arthur Carpenter, Jose Hernandez, Jorge Carrera, Hesham Khater, Eric Downing, Nicholas St. Hilaire, Shiva Sitaraman
Fielding the LANL third-generation Gas Cherenkov Detector (GCD-3) at the National Ignition Facility (NIF) revealed an
array of complex engineering challenges. Fielding the GCD-3 Detector in a 3.9 meter re-entrant Well on the NIF Target
Chamber required the development of a specialized detector deployment system named the WellDIM3.9m Diagnostic
Manipulator (WellDIM). The most stringent design requirement entailed a no-load/no-contact condition with the Well, which
dictated that all seismic loads be transferred to the Target Chamber port flange. The WellDIM transports the GCD-3 into the
Well at a distance of 3.9m from Target Chamber Center. The GCD-3 Detector, outfitted with additional shielding to mitigate
higher NIF backgrounds, will serve as a prototype for the future, heavily shielded “Super-GCD”.
The newest Gas Cherenkov Detector (GCD-3) diagnostic has completed its Phase I commissioning/milestone at the
National Ignition Facility (NIF). GCD-3 was fielded for several years at the Omega Laser Facility in its initial
configuration, before being moved to the NIF. Installation at the NIF involved optimization of GCD-3 for the higher
background environment and designing a new insertion carrier assembly. GCD-3 serves as the initial phase towards the
implementation of the “Super GCD” (SGCD) at the NIF. During this phase of development GCD-3 took measurements
from a re-entrant well, 3.9 meters from target chamber center (TCC). Plans to insert GCD-3 within 20 cm of TCC with a
Target and Diagnostic Manipulator (TANDM) will be discussed. Data was collected using a Photomultiplier Tube
(PMT) in combination with a Mach-Zehnder based recording system. These measurements were used to aid in shielding
analysis, validate MCNP models, and fuel design efforts for the SGCD. Findings from the initial data will be covered
extensively, including an in-depth look into sources of background and possible mitigation strategies. Ongoing
development of phase two, the addition of an ultra-high bandwidth Pulse Dilatation Photomultiplier Tube (PD-PMT),
will also be presented.
Neutron activation diagnostics are commonly employed as baseline neutron yield and relative spatial flux measurement instruments. Much insight into implosion performance has been gained by deployment of up to 19 identical activation diagnostic samples distributed around the target chamber at unique angular locations. Their relative simplicity and traceability provide neutron facilities with a diagnostic platform that is easy to implement and verify. However, the current National Ignition Facility (NIF) implementation relies on removable activation samples, creating a 1-2 week data turn-around time and considerable labor costs. The system described here utilizes a commercially-available lanthanum bromide (cerium-doped) scintillator with an integrated MCA emulator as the counting system and a machined zirconium-702 cap as the activation medium. The device is installed within the target bay and monitored remotely. Additionally, this system allows the placement of any activation medium tailored to the specific measurement needs. We discuss the design and function of a stand-alone and permanently installed neutron activation detector unit to measure the yield and average energy of a nominal 14 MeV neutron source with a pulse length less than one nanosecond.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.