Microwave Kinetic Inductance Detectors for optical and near-IR astronomy Kieran O’Brien University of Oxford

The UK Optical/UV MKID Team: Kieran O’Brien, Niranjan Thatte, Angela Taylor, Mike Jones, Ghassan Yassin (University of Oxford) Jo Bartlett, Ian Hepburn (Mullard Space Science Labs) (Stafford Withington (University of Cambridge)) UK MKIDs Team Kieran O'Brien, Fermilab MKID workshop, August Opto-mechanics/System Read-out Detectors Cryogenics

Building on existing capabilities;  Opt/IR instrument building o o o o o  Radio instrumentation o C-BASS  Detector development o Sub-mm Combine with other specialist groups  MSSL cryogenic group  Cambridge detector fabrication group Kieran O'Brien, Fermilab MKID workshop, August

Oxford experimental radio cosmology group Design and construction of radio technology for astrophysics Cryostat design (eg 4K rx using Sumitomo G-M coolers) In-house design of RF components: amplifiers, filters, hybrids, switches etc. Use of CASPER digital backend technology: ROACH I & II, iADCs, correlator & spectrometer firmware.

Example: C-BASS South Receiver Digital correlation polarimeter – two down-converted channels of 500 MHz sampled in 1 st and 2 nd Nyquist zones 2 x ROACH FPGA board each with 4 x 1 GS/s ADC inputs 64-channel spectrometer per ROACH channels in total ~ 4.5 GHz ~ ~ ~ ~ ~ ~ iADC/ ROACH iADC/ ROACH 1 GS/s MHz MHz

Example: RF components 5 GHz cryogenic notch filter Broadband amplifier (manufacture licenced to AtlanTec) Broadband 90-deg hybrid

Kieran O'Brien, Fermilab MKID workshop, August Designed to provide an interface to the user which can be set to a temperature within the range of 100 mK to 4 K. Provides continuous cooling Utilises two magnetic cooling chains  Fast operating Single module which bolts on to a 4 K interface Designed with ease of use in mind  Fully automated with Labview control system Magnetically shielded  Each magnet is a 2 T magnet Dimensions: 355 mm height, 120 mm width, 56 mm depth. Total mass: 8.3 kg  6.6 kg due to magnets and magnetic shields Millikelvin cryocooler (mKCC)

Dynamical mass studies Kieran O'Brien, Fermilab MKID workshop, August From Steeghs, et al Scorpius X-1 o Bright LMXB o Shows emission lines from irradiated disk o Bowen Blend lines are fluorescence lines on donor star o Use doppler shift of lines to constrain the mass of the compact object o Orbital period = 18.9hrs

Dynamical mass studies Kieran O'Brien, Fermilab MKID workshop, August From Steeghs, et al Scorpius X-1 o Bright LMXB o Shows emission lines from irradiated disk o Bowen Blend lines are fluorescence lines on donor star o Use doppler shift of lines to constrain the mass of the compact object o Orbital period = 18.9hrs

Short Period systems Kieran O'Brien, Fermilab MKID workshop, August MAXI J1659–152: o 2.4hr orbital period (Kuulkers et al, 2013), shortest period Black-hole X- ray binary o r’ = 23.7 (Kong, 2012) s/n ~1 with X- shooter in 2.4hrs Ultra-compact X-ray binaries would have even shorter periods (few minutes) and fainter lines. Possible SNIa progenitors and important GW sources.

The enemy: Read-out noise Kieran O'Brien, Fermilab MKID workshop, August Example of effects of read-out noise in short-period systems. KIDSPEC will have much larger wavelength coverage, enabling the combination of multiple lines. Figure courtesy of T. Marsh

Instrument requirements Single object Medium spectral resolution (R > 5000) to distinguish velocity components in the emission lines of Interacting Binary systems (and many other applications) Wide passband ( μm) to capture as much of the SED of the object as possible simultaneously Good temporal resolution (< 0.1secs) to sample characteristic time-scales (frequencies of variability, light-travel times, orbital periods) in Interacting Binaries Low noise to avoid penalty of time resolution Optimizes collecting power of large telescopes, eg Keck, TMT Kieran O'Brien, Fermilab MKID workshop, August

X-Shooter X-Shooter is a 2 nd generation instrument at ESO’s 8.2m VLT in Chile Designed as very efficient, single-target, intermediate- resolution spectrograph Covers the spectral range from 300 to 2500 nm in a single exposure. Dichroic splits in 3 arms. Intermediate spectral resolution R ~ 4,000 – 17,000 depending on wavelength and slit width with fixed echelle spectral format (prism cross-dispersers) in the three arms. Kieran O'Brien, Fermilab MKID workshop, August

Example of X-shooter data Kieran O'Brien, Fermilab MKID workshop, August Spectral resolution 6000, 10400, 6200 Seeing 0.6” (under-filled slit) Velocity resolution 2-5kms -1 depending on wavelength

Kieran O'Brien, Fermilab MKID workshop, August Optical Arm IR Arm

KIDspec or ‘super’-X-Shooter High throughput spectrograph, with echelle grating in low order (<20) to achieve spectral resolution of 5- 10,000 Cross-disperser is replaced by energy resolution of MKIDs Photon counting detector allows for excellent background subtraction (a problem for eg. X- shooter/VLT) Combined with an image slicer, could give Integral- Field Spectroscopy as well. Kieran O'Brien, Fermilab MKID workshop, August See also, Cropper et al., 2003

Order-sorting scheme Kieran O'Brien, Fermilab MKID workshop, August

Summary UK has significant experience in related technologies Plan to bring together to build KIDSPEC, a single object, high throughput medium resolution optical/IR spectrograph capable of exploiting the unique capabilities of MKIDs Timescale Feb 2014 – build/test read-out system July 2014 – lab demonstration of MKID in mKCC Summer 2014 – apply for national funding 2017/8 – deployment at telescope Kieran O'Brien, Fermilab MKID workshop, August