Spontaneous generation of athermal phonon bursts within bulk silicon causing excess noise, low energy background events, and quasiparticle poisoning in superconducting sensors
Abstract
Solid state phonon detectors used in the search for dark matter and coherent neutrino nucleus interactions (CE ν NS) require excellent energy resolution (eV-scale or below) and low backgrounds. An unknown source of phonon bursts, the low energy excess (LEE), dominates other above-threshold backgrounds and generates excess shot noise from subthreshold bursts. In this paper, we measure these phonon bursts for 12 days after cooldown in two nearly identical 1 cm2 silicon detectors that differ only in the thickness of their substrate (1 vs 4 mm thick). We find that both the channel-correlated shot noise and near-threshold shared LEE relax with time since cooldown. Additionally, both the correlated shot noise and LEE rates scale linearly with substrate thickness. When combined with previous measurements of other silicon phonon detectors with different substrate geometries and mechanical support strategies, these measurements strongly suggest that the dominant source of both above and below threshold LEE is the bulk substrate. By monitoring the relation between bias power and excess phonon shot noise, we estimate that the energy scale for subthreshold noise events is 0.68±0.38 meV. In our final dataset, we report a world-leading energy resolution of 258.5 ± 0.4 meV in the 1 mm thick detector. Simple calculations suggest that these silicon substrate phonon bursts are likely a significant source of quasiparticle poisoning in superconducting qubits operated in well shielded and vibration free environments.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (29)
C. L. Chang
Argonne National Laboratory 1 , 9700 S Cass Ave, Lemont, Illinois 60439,
Y.-Y. Chang
Department of Physics, University of California Berkeley 4 , 366 LeConte Hall 7300, Berkeley, California 94720,
M. Garcia-Sciveres
W. Guo
S. A. Hertel
University of Massachusetts, Amherst Center for Fundamental Interactions and Department of Physics 9 , 101 Stockbridge Hall, 80 Campus Center Way, Amherst, Massachusetts 01003-9337,
X. Li
J. Lin
M. Lisovenko
Argonne National Laboratory 1 , 9700 S Cass Ave, Lemont, Illinois 60439,
R. Mahapatra
Department of Physics and Astronomy, Texas A&M University 10 , 4242 TAMU, 578 University Dr., College Station, Texas 77843-4242,
W. Matava
Department of Physics, University of California Berkeley 4 , 366 LeConte Hall 7300, Berkeley, California 94720,
D. N. McKinsey
Department of Physics, University of California Berkeley 4 , 366 LeConte Hall 7300, Berkeley, California 94720,
P. K. Patel
University of Massachusetts, Amherst Center for Fundamental Interactions and Department of Physics 9 , 101 Stockbridge Hall, 80 Campus Center Way, Amherst, Massachusetts 01003-9337,
B. Penning
Department of Physics, University of Zurich 11 , Winterthurerstrasse 190, 8057 Zurich,
H. D. Pinckney
University of Massachusetts, Amherst Center for Fundamental Interactions and Department of Physics 9 , 101 Stockbridge Hall, 80 Campus Center Way, Amherst, Massachusetts 01003-9337,
M. Platt
Department of Physics and Astronomy, Texas A&M University 10 , 4242 TAMU, 578 University Dr., College Station, Texas 77843-4242,
M. Pyle
Department of Physics, University of California Berkeley 4 , 366 LeConte Hall 7300, Berkeley, California 94720,
Y. Qi
M. Reed
Department of Physics, University of California Berkeley 4 , 366 LeConte Hall 7300, Berkeley, California 94720,
I. Rydstrom
Department of Physics, University of California Berkeley 4 , 366 LeConte Hall 7300, Berkeley, California 94720,
R. K. Romani
Department of Physics, University of California Berkeley 4 , 366 LeConte Hall 7300, Berkeley, California 94720,
B. Sadoulet
Department of Physics, University of California Berkeley 4 , 366 LeConte Hall 7300, Berkeley, California 94720,
B. Serfass
Department of Physics, University of California Berkeley 4 , 366 LeConte Hall 7300, Berkeley, California 94720,
P. Sorensen
Lawrence Berkeley National Laboratory 5 , 1 Cyclotron Rd., Berkeley, California 94720,
B. Suerfu
International Center for Quantum-Field Measurement Systems for Studies of the Universe and Particles (QUP, WPI), High Energy Accelerator Research Organization (KEK) 6 , Oho 1-1, Tsukuba, Ibaraki 305-0801,
V. Velan
Lawrence Berkeley National Laboratory 5 , 1 Cyclotron Rd., Berkeley, California 94720,
G. Wang
Y. Wang
M. R. Williams
Lawrence Berkeley National Laboratory 5 , 1 Cyclotron Rd., Berkeley, California 94720,
V. G. Yefremenko
Argonne National Laboratory 1 , 9700 S Cass Ave, Lemont, Illinois 60439,