UK contribution to B-Pol Lucio Piccirillo for the UK B-Pol team Paris, 25 October 2006

The UK collaboration: University of Manchester Oxford University Cambridge University Cardiff University Imperial College RAL Edinburgh

UK institutions  main involvements in WGs Manchester:Theory/Foreground/Instrument Cambridge:Theory/Foreground/Instrument Cardiff:Instrument Edinburgh:Theory Imperial:Theory Oxford:Theory/Foreground/Instrument RAL:Instrument

UK institutions and people (partial list): ManchesterOxfordCambridgeCardiff Lucio Piccirillo (I)Ghassan Yassin (I) Stafford Withington (I) Phil Mauskopf (I) Giampaolo Pisano (I) Joe Silk (T) Anthony Lasenby (T) Giorgio Savini (I) Bruno Maffei (I) Pedro Ferreira (T) George Efstathiou (T) Walter Gear (I) Simon Melhuish (I) Angela Taylor (F) Mike Hobson(F) Peter Ade (I) Richard Battye (T)Michael Jones (I) Michael Brown (I) Richard Davis (I) Anthony Challinor (T) A & P Wilkinson (I) Paddy Leahy (F) Rod Davies (F) Bob Watson (I) Neil Roddis (I) Danielle Kettle (E&E) (I) Mo Missous (E&E) (I)

UK institutions: Imperial C.EdinburghRAL Andrew Jaffe (T) Andy Taylor (T) Brian Ellison (I) Carlo Contaldi (T) John Peacock Patricia Castro (T) Alan Heavens

B-Pol will be a satellite mission attempting the detection of CMB (curl) B–modes polarization. B–modes are generated by the primordial background of gravitational waves. Inflation (so far) is the only mechanism able to generate these long-wavelength gravity waves (IGWs – Inflationary Gravitational Waves) Amplitude of IGW  V(  ) – value of inflaton potential during inflation Amplitude of B-modes directly constraints the energy scale of inflation  link cosmology – particle physics

Theoretical studies (science) Instrument specifications (parameters) Instrument performances (tolerances) Technology Prototypes testing Final Instrument test design

UK is interested in all working groups: Science Working Group Foreground Working Group Instrument Working Group

UK is interested in all working groups: Science Working Group Foreground Working Group Instrument Working Group will learn more about UK contribution in these areas the next two days

Track Record UK led:VSA (CAM, MAN) QuAD (CAR) (2 nd gen.) CLOVER (CAR, CAM, MAN, OX) (3 rd gen.) Significant UK contribution: Planck LFI & HFI, Boomerang, MAXIMA/MAXIPOL, CBI, Archeops 1 st gen. CMB polarimetry: POLAR, COMPASS RAL  biggest UK / one of European largest space science department. Excellent mm/sub-mm wave technical expertise and heritage CAM, OX, Imperial, MAN etc.  strong theory groups

potential UK role in European B-Pol 1.Experience (hardware) for major state-of-the-art CMB polarization experiments 2.Detector design, manufacturing & testing facilities in CAM/OX/MAN/CAR. Planar devices 3.sub-K cryogenics 4.RF components (Horns, OMTs, Phase switches, etc.) 5.Software: instrument simulations, observing strategies, data analysis pipeline, parameter estimations, etc.

UK strength in Instrument Design Heterodyne and bolometric interferometry, imaging arrays Telescope design: physical optics simulations, experience in mirror and mount fabrication Microwave components (horns, OMTs, polarimeters) Superconducting planar circuits (phase switches, filters, radial probes, finlines) Detector physics and fabrication (TES, KIDS, SIS) Integrated Low Noise Amplifiers

UK interest in the Instrument Working Group : 1.Theoretical studies of systems and sub-systems (optics, cryogenics, antennas, detectors & read-out, etc.) 2.R&D/prototyping of key technologies (polarimeter components, detectors, etc.) 3.Testing from prototypes to flight hardware (optics, cryogenics, RF, etc.) 4.Level 1 data handling

Specialized manufacturing facilities in UK 1.Cambridge detector lab: superconducting devices (TES, SIS, KIDs, SQUIDs, etc.) 2.Manchester E&E semiconductor facilities (InP, GaAs, etc.) 3.Cardiff filter lab 4.Manchester/Chase Res.: Sub-K closed-cycle sorption coolers ( 3 He, 3 He/ 4 He, 3 He/ 4 He/ 3 He, mini-dilutors, gas switches, etc.) 5.RAL: precision CNC machining

An example of of mm/sub-mm UK capability/facilities: RAL 1.Electroplating & electroforming (space qualified) 2.Microwave calibration loads 3.Lapping 4.Interferometer Grids 5.Micro-drilling 6.Non contact metrology see

Superconducting TES Detector Arrays for B-Pol Full superconducting detector development facility available in UK: currently being used to manufacture microstrip-coupled TES detector arrays for CLOVER.

TES development for CLOVER 97GHz Finline microstrip-coupled TES detector for CLOVER. The device was designed, manufactured, and tested by the UK CLOVER consortium. Radial-probe detectors are being developed for the short- wavelength channels. High yields with well controlled device parameters are being achieved. DRIE is used to achieve the Si micromachining.

Molecular Beam Epitaxy facility in Manchester

Specialised testing facilities in UK: 1.Man (E&E + Physics) – Agilent lab for VNA RF (up to W- band) testing – on chip and in wave-guide – room temperature to 4K 2.Cardiff FTS lab + 90/150 mm VNA mK Cam/Man/Car detector test beds 4.Car/Man mm/sub-mm anechoic chambers

micro/mm-wave Agilent labs in Manchester

Summary of main experimental UK activities: 1.detector manufacturing 2.quasi optical filters 3.e.m. simulations and manufacturing of optics 4.e.m. simulations and manufacturing of RF components (waveguide & u-strip) 5.design and realization of sub-K cryogenics 6.test beds for large format arrays 7.cryogenic test beds for mm/sub-mm components

Summary of some (not all!) relevant UK research activities: 1.superconducting planar phase switches 2.InP HEMT polarimeter on chip 3.Finlines and radial probes 4.sorption (0.25K) and dilution (0.05K) systems 5.CEB, KIDs detector development 6.RF components (OMTs, Horns, etc.)... and much more...

Some final considerations: 1.Detecting B-modes will be hard – even from space 2.A complementary ground-based/balloon experiments at the high/low frequency range might be needed on some selected sky regions with high sensitivity and high angular resolution 3.Sensitivity but control of systematic effects (not only instrumental) will be a key factor  these two requirements somehow compete with each other... 4.When the first generation B-modes experiments will start producing data we will probably have a much better idea (2-3 years from now?) 5.Calibration.... data analysis!?!

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Possible B-Pol architecture: one telescope per frequency uses mirrors instead of lenses can “hide” components behind the large 70 GHz primary re-use a lot of design studies carried for CLOVER can correct XPol because of 2 mirrors Somehow large cryostat (1.6 m diam.) might be same weight (or lighter) than lenses option mirrors can be radiatively cooled (?)... ? drawing by A. Cevolani

Ultrasensitive Cold-Electron Bolometer (CEB) Chalmers University, Leonid Kuzmin Collaborators: Cambridge University, Oxford University, Cardiff University, IPHT, Jena We have achieves a record sensitivity of the Cold-Electron Bolometer (CEB): the noise equivalent power (NEP) of better than W/Hz 1/2 has been measured. Theoretical estimations: NEP= W/Hz 1/2 The CEB consisting of two SIN tunnel junctions and a nano-absorber has been fabricated using nano-facilities of MC2. A new generation of supersensitive detectors is to understand the mysterious nature of Dark Matter and Dark Energy. We participate in balloon projects OLIMPO and CLOVER and balloon project PILOT led by CESR (Toulouse). We are invited to demonstrate CEB for ESA Space project SPICA: an ultimate NEP= W/ Hz 1/2 for spectroscopy should be realized for this purpose. I. Agulo, L. Kuzmin, and M. Tarasov, “Attowatt Sensitivity of the Cold-Electron Bolometer”, subm. to Appl. Phys. Lett (2006) Figure.. Data… Strip width = 0.2  m

Cold-Electron Bolometer (CEB) with Capacitive Coupling to the Antenna 100 nm

C l OVER is a ground-based experiment that will attempt to measure the primordial B-mode polarization power spectrum of the CMB for r > 0.01 covering a multipole range 20 < l < CLOVER path from theory to instrument manufacturing

C l OVER will: 1.Map the Stokes parameters over around 700 deg 2 of the sky 2.Observe at 97, 150 and 225 GHz with a 10-arcmin FWHM beam 3.Make sample-variance-limited measurements of the, and power spectra up to multipoles l ~ Measure at high significance the B-mode power spectrum due to weak gravitational lensing 5.Characterize the polarization properties of galactic foregrounds

Control of systematic errors 1.Achieve the necessary raw sensitivity. Number of photons collected  number of horns & detectors  large focal plane arrays (160 horns at 97 GHz, 256 horns at 150 GHz, 256 horns at 225 GHz) 2.Develop experimental techniques to keep systematic errors below the statistical errors 3.Build from the experience in, and. power spectrum determination has never been attempted down to the required level for a significant detection. 4.The signal is small, really small! r = T/S = 0.01 means that we are looking for rms signals of the order of 30 nK. 5.We are designing Clover to keep systematic effects at a level of 10% (3 nK.....) 6.DASI, CBI and CAPMAP have observed from the ground to a level of 1  K rms. We need to do 30 times better! times more sensitive is achievable considering Clover number of detectors (1184) with better intrinsic noise (about 200  K s 1/2 )

CharacteristicRequirements r0.01 l coverage 20 < l < 1000 Observing (integration time)2 (1) year Beamsize for all frequency bands 10 arcmin (or  15 arcmin) Survey area700 deg 2 Final map shapeMinimize E – B mixing Frequency bands97, 150, 225 GHz Required scan/modulation typePolarization, az/el/pol axis Single detector measureT, Q and U Noise limit Photon noise from sky  intrinsic noise intrinsic NET at 97, 150, 225 GHz 125, 195 and 619  K  sec Ratio of detectors at three frequency bands 160 : 256 : 256 (Polarized) ground signal rejection< -100 dB wrt main beam Spillover limit at 97, 150, 225 GHz1.4%, 2%, 3.5% Beam ellipticityeccentricity < 0.3 Residual cross-polarization- 50 dB Polarimeter efficiency> 90% Residual instrument polarization< 0.03%

Additional systematic effects: 1.Polarized side-lobes (response at Galactic emission)  z-axis rotation, polarization modulation  (dT  B) must be kept < Polarization angle  (dT  B) must know angle better than a fraction of degree 3.Sources of optical power within the field of view must be kept constant <3  K (assumes difference in emissivities) 4.Dilution fridge temperature stability < 1 nK 5.Relative pointing between different horns in the same focal plane. It has to be better than 0.1 arcsec to keep dT  B below 3 nK

Very general plan: 1.Theoretical studies (mostly done) on how to build the instrument to satisfy the requirements 2.Build a test instrument (Single-Pixel Demonstrator) to test mostly the detectors and cold optics, cryogenics, read-out and electronics 3.Integrate the Clover prototype (SPD + mount) and extended tests 4.Move Clover prototype to Atacama  test site 5.Final development of the 3 instruments

Clover SPD

3 focal planes WG polarization rotation Wave plate options

Single-shot miniature self- contained dilution refrigerator. 3  W cooling power at 100 mK Electrically operated with sorption pumps and gas heat-switches No external gas-handling system Fast pre-cooling times

97 GHz 225 GHz 150 GHz Clover optical assemblies

Clover on a single mount

Clover radiation shielding