Target allocation yields for massively multiplexed spectroscopic surveys with fibers [electronic resource].

Published: Washington, D.C. : United States. Dept. of Energy. High Energy Physics Division, 2014.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description: 915,023 : digital, PDF file
Additional Creators: Fermi National Accelerator Laboratory, United States. Department of Energy. High Energy Physics Division, and United States. Department of Energy. Office of Scientific and Technical Information

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Summary

We present Simulated Annealing fiber-to-target allocation simulations for the proposed DESI and 4MOST massively multiplexed spectroscopic surveys, and for both Poisson and realistically clustered mock target samples. We simulate both Echidna and theta-phi actuator designs, including the restrictions caused by the physical actuator characteristics during repositioning. For DESI, with theta-phi actuators, used in 5 passes over the sky for a mock ELG/LRG/QSO sample, with matched fiber and target densities, a total target allocation yield of 89.3% was achieved, but only 83.7% for the high-priority Ly-alpha QSOs. If Echidna actuators are used with the same pitch and number of passes, the yield increases by 5.7% and 16% respectively. Echidna also allows a factor-of-two increase in the number of close Ly-alpha QSO pairs that can be observed. Echidna spine tilt causes a variable loss of throughput, with average loss being the same as the loss at the rms tilt. With a natural tilt minimization scheme, we find an rms tilt always close to 0.58 x maximum. There is an additional but much smaller defocus loss, equivalent to an average defocus of 30microns. These tilt losses offset the gains in yield for Echidna, but because the survey strategy is driven by the higher priority targets, a clear survey speed advantage remains. For 4MOST, high and low latitude sample mock catalogs were supplied by the 4MOST team, and allocations were carried out with the proposed Echidna-based positioner geometry. At high latitudes, the resulting target completeness was 85.3% for LR targets and 78.9% for HR targets. At low latitude, the target completeness was 93.9% for LR targets and 71.2% for HR targets.

Report Numbers

E 1.99:arxiv:1406.1787
E 1.99: fermilab-pub-14-395-a
fermilab-pub-14-395-a
arxiv:1406.1787

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Note

Published through SciTech Connect.
08/05/2014.
"arxiv:1406.1787"
" fermilab-pub-14-395-a"
"1299860"
Proceedings of SPIE - The International Society for Optical Engineering 9150 ISSN 0277-786X FT
Saunders, Will; Smedley, Scott; Gillingham, Peter; Forero-Romero, Jaime; Jouvel, Stephanie; Nord, Brian.

Funding Information

AC02-07CH11359

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