The Next Generation Microshutter Array (NGMSA) is an all-electrostatic actuated, programmable light transmission device used for multi-object spectroscopy. The latest NGMSA is designed to operate by ...applying a voltage difference between the shutter blade electrode and a single back wall electrode. We investigate the effects of different wall electrode configurations and present a bi-electrode design that allows reliable shutter actuation at a voltage difference of 70V.
Display omitted
•The effects of electrode configurations for the NGMSA are investigated.•Current NGMSA design requires pulsed actuation to overcome low electrostatic force.•A front wall electrode increases electrostatic force on the shutter blade.•A bi-electrode design is proposed to reduce actuation power requirements.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
ABSTRACT
We present analytical and numerical models of the bright long GRB 210822A at z = 1.736. The intrinsic extreme brightness exhibited in the optical, which is very similar to other bright GRBs ...(e.g. GRBs 080319B, 130427A, 160625A 190114C, and 221009A), makes GRB 210822A an ideal case for studying the evolution of this particular kind of GRB. We use optical data from the RATIR instrument starting at T + 315.9 s, with publicly available optical data from other ground-based observatories, as well as Swift/UVOT, and X-ray data from the Swift/XRT instrument. The temporal profiles and spectral properties during the late stages align consistently with the conventional forward shock model, complemented by a reverse shock element that dominates optical emissions during the initial phases (T < 300 s). Furthermore, we observe a break at T = 80 000 s that we interpreted as evidence of a jet break, which constrains the opening angle to be about θj = (3–5) degrees. Finally, we apply a machine-learning technique to model the multiwavelength light curve of GRB 210822A using the afterglowpy library. We estimate the angle of sight θobs = (6.4 ± 0.1) × 10−1 degrees, the energy E0 = (7.9 ± 1.6) × 1053 erg, the electron index p = 2.54 ± 0.10, the thermal energy fraction in electrons ϵe = (4.63 ± 0.91) × 10−5 and in the magnetic field ϵB = (8.66 ± 1.01) × 10−6, the efficiency χ = 0.89 ± 0.01, and the density of the surrounding medium n0 = 0.85 ± 0.01 cm−3.
We have recently witnessed the first multi-messenger detection of colliding neutron stars through gravitational waves (GWs) and electromagnetic (EM) waves (GW 170817) thanks to the joint efforts of ...LIGO/Virgo and Space/Ground-based telescopes. In this paper, we report on the RATIR follow-up observation strategies and show the results for the trigger G194575. This trigger is not of astrophysical interest; however, it is of great interest to the robust design of a follow-up engine to explore large sky-error regions. We discuss the development of an image-subtraction pipeline for the six-color, optical/NIR imaging camera RATIR. Considering a two-band (i and r) campaign in the fall of 2015, we find that the requirement of simultaneous detection in both bands leads to a factor ∼10 reduction in false alarm rate, which can be further reduced using additional bands. We also show that the performance of our proposed algorithm is robust to fluctuating observing conditions, maintaining a low false alarm rate with a modest decrease in system efficiency that can be overcome utilizing repeat visits. Expanding our pipeline to search for either optical or NIR detections (three or more bands), considering separately the optical riZ and NIR YJH bands, should result in a false alarm rate 1% and an efficiency 90%. RATIR's simultaneous optical/NIR observations are expected to yield about one candidate transient in the vast 100 deg2 LIGO error region for prioritized follow-up with larger aperture telescopes.
Excess heat capacity in a bolometric detector has the consequence of increasing or leading to multiple device time constants. The Mo/Au bilayer transition edge sensor (TES) bolometric detectors ...initially fabricated for the high resolution mid-infrared spectrometer (HIRMES) exhibited two response thermalization scales, one of which is a few times longer than estimates based upon the properties of the bulk materials employed in the design. The relative contribution of this settling time to the overall time response of the detectors is roughly proportional to the pixel area, which ranges between ∼0.3 and 2.6 mm 2 . Use of laser ablation to remove sections of the silicon membranes comprising the pixels results in a detector response with a smaller contribution from the secondary time constant. Additional information about the nature of this excess heat capacity is gleaned from glancing incidence X-ray diffraction, which reveals the presence of molybdenum silicides near the silicon surface which is a consequence of the bi-layer deposition. Quantitative analysis of the concentration of excess molybdenum, estimated with secondary ion mass spectroscopy, is commensurate to the additional heat capacity needed to explain the anomalous time response of the detectors.
Next Generation Microshutter Array (NGMSA) is an electrostatically operated micro electro-mechanical system (MEMS) device for programmable spatial light filtering application. Original microshutter ...array (MSA), which is magnetically operated, was developed for the James Webb Space Telescope (JWST) NIRSpec multi-object spectrometer, and NGMSA inherited its design from the original MSA. Even though there has been incremental design changes in order to achieve stable electrostatic actuation, NGMSA operation still requires further study. Previous simulation efforts to model NGMSA's actuation mechanics allowed to gain only general understanding of the behavior due to inadequate simulation and experimental methods. In this study, a novel electrostatic numerical simulation model is presented using COMSOL Multiphysics to accurately predict microshutter's motion during actuation. The new model addresses all the issues that hinder realistic modeling. Current Microshutter Array yield and operation performance issues related to fabrication process are analyzed with this numerical model and a potential optimized design is proposed. The result shows that a few m shorter shutter blade allows stable electrostatic actuation as well as better tolerance to the fabrication accuracy. Also, modified blade side shape reduces undesirable asymmetrical motions which cause failed stuck shutters.
Long-duration gamma-ray bursts (GRBs) are powerful cosmic explosions, signaling the death of massive stars. Among them, GRB 221009A is by far the brightest burst ever observed. Because of its ...enormous energy (
≈ 10
erg) and proximity (
≈ 0.15), GRB 221009A is an exceptionally rare event that pushes the limits of our theories. We present multiwavelength observations covering the first 3 months of its afterglow evolution. The x-ray brightness decays as a power law with slope ≈
, which is not consistent with standard predictions for jetted emission. We attribute this behavior to a shallow energy profile of the relativistic jet. A similar trend is observed in other energetic GRBs, suggesting that the most extreme explosions may be powered by structured jets launched by a common central engine.
2-D Electrostatic Actuation of Microshutter Arrays Burns, Devin E.; Oh, Lance H.; Li, Mary J. ...
Journal of microelectromechanical systems,
2016-Feb., 2016-2-00, 20160201, Volume:
25, Issue:
1
Journal Article
Peer reviewed
Electrostatically actuated microshutter arrays consisting of rotational microshutters (shutters that rotate about a torsion bar) were designed and fabricated through the use of models and ...experiments. Design iterations focused on minimizing the torsional stiffness of the microshutters while maintaining their structural integrity. Mechanical and electromechanical test systems were constructed to measure the static and dynamic behavior of the microshutters. The torsional stiffness was reduced by a factor of four over initial designs without sacrificing durability. The analysis of the resonant behavior of the microshutters demonstrates that the first resonant mode is a torsional mode occurring around 3000 Hz. At low vacuum pressures, this resonant mode can be used to significantly reduce the drive voltage necessary for actuation requiring as little as 25 V. The 2-D electrostatic latching and addressing was demonstrated using both a resonant and a pulsed addressing scheme.
Abstract
We report observations of the optical counterpart of the long gamma-ray burst (GRB) GRB 230812B and its associated supernova (SN) SN 2023pel. The proximity (
z
= 0.36) and high energy (
E
γ
...,iso
∼ 10
53
erg) make it an important event to study as a probe of the connection between massive star core collapse and relativistic jet formation. With a phenomenological power-law model for the optical afterglow, we find a late-time flattening consistent with the presence of an associated SN. SN 2023pel has an absolute peak
r
-band magnitude of
M
r
= −19.46 ± 0.18 mag (about as bright as SN 1998bw) and evolves on quicker timescales. Using a radioactive heating model, we derive a nickel mass powering the SN of
M
Ni
= 0.38 ± 0.01
M
⊙
and a peak bolometric luminosity of
L
bol
∼ 1.3 × 10
43
erg s
−1
. We confirm SN 2023pel’s classification as a broad-line Type Ic SN with a spectrum taken 15.5 days after its peak in the
r
band and derive a photospheric expansion velocity of
v
ph
= 11,300 ± 1600 km s
−1
at that phase. Extrapolating this velocity to the time of maximum light, we derive the ejecta mass
M
ej
= 1.0 ± 0.6
M
⊙
and kinetic energy
E
KE
=
1.3
−
1.2
+
3.3
×
10
51
erg
. We find that GRB 230812B/SN 2023pel has SN properties that are mostly consistent with the overall GRB-SN population. The lack of correlations found in the GRB-SN population between SN brightness and
E
γ
,iso
for their associated GRBs across a broad range of 7 orders of magnitude provides further evidence that the central engine powering the relativistic ejecta is not coupled to the SN powering mechanism in GRB-SN systems.
PDF
