Introduction to the detection technology of Ali CMB polarization telescope

Liu, Cong‐Zhan; Li, Zhangwei; Liu, Yang; Li, Yongping; Li, Siyu; Li, Hong; Gao, G. H.; Zhang, Xinmin

doi:10.1007/s41605-017-0013-3

Cited by 13 publications

(13 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Within a given trial the height of the SWS is by-and-large a monotonically increasing function of F cum ; see Figure 5. The trial pairs (1,3), (2,4), (5,7), and (6,8), where the curves overlap, share the same N l ; the repetition rate and scan speed were adjusted to maintain the same F cum . The similarity between the curves suggest that a single underlying model may account for all the data; this is the topic of Section 4.…”

Section: Ignoring Edge Effectsmentioning

confidence: 99%

“…For a wide range of millimeter and sub-millimeter (MSM) astrophysical instruments there is a need for broad-band, cryogenically robust, anti-reflection coatings (ARC) [1][2][3][4][5][6][7][8][9]. Fabricating subwavelength structures (SWS) directly on the material of interest is an ARC technique that alleviates the need for several layers of materials and glues with various indices of refraction.…”

Section: Introductionmentioning

confidence: 99%

“…The implementation of laser-ablated SWS ARC on alumina and sapphire for current and next generation instruments has been limited by slow fabrication rate. Optical elements including lenses, filters, and half-wave plates in several instruments have diameters near or larger than 500 mm [2,[4][5][6]. Previously we reported volume removal rate of 1.0 mm 3 /min on alumina and up to 2.2 mm 3 /min on sapphire [23,27].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Picosecond Laser Ablation of Millimeter-Wave Subwavelength Structures on Alumina and Sapphire

Wen,

Fadeeva,

Hanany

et al. 2021

Preprint

View full text Add to dashboard Cite

We use a 1030 nm laser with 7 ps pulse duration and average power up to 100 W to ablate pyramid-shape subwavelength structures (SWS) on alumina and sapphire. The SWS give an effective and cryogenically robust anti-reflection coating in the millimeter-wave band. We demonstrate average ablation rate of up to 34 mm 3 /min and 20 mm 3 /min for structure heights of 900 µm and 750 µm on alumina and sapphire, respectively. These rates are a factor of 34 and 9 higher than reported previously on similar structures. We propose a model that relates structure height to cumulative laser fluence. The model depends on the absorption length δ, which is assumed to depend on peak fluence, and on the threshold fluence φ th . Using a best-fit procedure we find an average δ = 630 nm and 650 nm, and φ th = 2.0 +0.5 −0.5 J/cm 2 and 2.3 +0.1 −0.1 J/cm 2 for alumina and sapphire, respectively, for peak fluence values between 30 and 70 J/cm 2 . With the best fit values, the model and data values for cumulative fluence agree to within 10%. Given inputs for δ and φ th the model is used to predict average ablation rates as a function of SWS height and average laser power.

show abstract

Section: Ignoring Edge Effectsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Picosecond Laser Ablation of Millimeter-Wave Subwavelength Structures on Alumina and Sapphire

Wen,

Fadeeva,

Hanany

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…The AliCPT-1 telescope is a dichroic refractor of aperture 70 cm covering 95/150 GHz, with a three-axis driving mount scanning at a speed of 5°/s in azimuth. AliCPT-1 adopts transition-edge sensor (TES) bolometers used widely in current CMB polarization experiments [ 11 ], and takes superconducting quantum interference devices (SQUIDs) as the cryogenic readout. The sensors and their readout will be packaged into highly integrated modules, and each module contains 1704 TES sensors.…”

Section: Alicpt and Its Scientific Goalsmentioning

confidence: 99%

Probing primordial gravitational waves: Ali CMB Polarization Telescope

Liu

et al. 2018

National Science Review

Self Cite

View full text Add to dashboard Cite

In this paper, we will give a general introduction to the project of Ali CMB Polarization Telescope (AliCPT), which is a Sino-US joint project led by the Institute of High Energy Physics (IHEP) and involves many different institutes in China. It is the first ground-based cosmic microwave background (CMB) polarization experiment in China and an integral part of China's Gravitational Waves Program. The main scientific goal of AliCPT project is to probe the primordial gravitational waves (PGWs) originated from the very early Universe.The AliCPT project includes two stages. The first stage referred to as AliCPT-1, is to build a telescope in the Ali region of Tibet with an altitude of 5,250 meters. Once completed, it will be the worldwide highest ground-based CMB observatory and open a new window for probing PGWs in northern hemisphere. AliCPT-1 telescope is designed to have about 7,000 TES detectors at 95GHz and 150GHz. The second stage is to have a more sensitive telescope (AliCPT-2) with the number of detectors more than 20,000.Our simulations show that AliCPT will improve the current constraint on the tensor-to-scalar ratio r by one order of magnitude with 3 years' observation. Besides the PGWs, the AliCPT will also enable a precise measurement on the CMB rotation angle and provide a precise test on the CPT symmetry. We show 3 years' observation will improve the current limit by two order of magnitude. * Invited Paper for N ational Science Review 1 BICEP2 collaboration [6] announced in 2014 the detection of B-mode, which however turns out to be the dust emissions dominate, not the signal of PGWs [7].From the aerial view around Ali astronomical observatory at A1 point (left panel of Figure 4), we can see that, AliCPT site at B1 is not far from A1 point, the distance between them is only about 1km. The concrete road

show abstract

“…Therefore, ground-based CMB experiments are usually carried out at high altitude with very dry air [29]. Even on high ridges, subject to the presence of the atmosphere, observations are usually performed only in a few band windows: below 50 GHz, around 95, 150 GHz and above 200 GHz [29,30]. For example, BICEP1 has observed in two frequencies of 100 GHz and 150 GHz, BICEP2 in 150GHz, even for South Pole telescope, a large aperture CMB camera, hold only three channels of 95, 150 and 220 GHz, centered around atmospheric windows, far fewer than space projects.…”

Section: Introductionmentioning

confidence: 99%

Detecting Primordial Gravitational Waves: a forecast study on optimizing frequency distribution of next generation ground-based CMB telescope

et al. 2020

Eur. Phys. J. C

Self Cite

View full text Add to dashboard Cite

Probing primordial gravitational waves is one of the core scientific objectives of the next generation CMB polarization experiment. Integrating more detector modules on the focal plane and performing high accurate observations are the main directions of the next generation CMB polarization telescope, like CMB S4. Also, multi-band observation is required by foreground analysis and reduction, as it is understood that foregrounds have become the main obstacles of CMB polarization measurements. However, ground observation is limited by the atmospheric window and can be usually carried out in one or two bands, like what BICEP or Keck array have done in the south pole. In this paper, we forecast the sensitivity of tensor-to-scalar ratio r that may be achieved by a multi-frequency CMB polarization experiment, basing on which to provide guidance for further expanding frequency bands and optimize the focal plane of a telescope. At the same time, the realization of having two frequency bands in one atmospheric window is discussed. With fixed number of detectors, the simulation results show that, in order to get a good limit, more frequency bands are needed. Better constraints can be obtained when it includes at least three bands, i.e., one CMB channel (95 GHz) + one dust channel (high frequency) and one synchrotron channel (low frequency). For example, 41 + 95 + 220 GHz, which is better than only focusing around the CMB band, like 85 + 105 + 150 GHz, and 95 + 135 + 155 GHz, and this frequency combination is even better than the combination of 41 + 95 + 150 + 220 GHz. As CMB S4 plans to consider two frequency bands in each atmospheric window, and along this way, we find that one CMB band and more bands in synchrotron and dust channels are helpful, for example, 2 bands in lower frequency, 30 + 41 GHz, 2 bands in higher frequency, 220 + 270 GHz, i.e. 30 + 41

show abstract

Introduction to the detection technology of Ali CMB polarization telescope

Cited by 13 publications

References 13 publications

Picosecond Laser Ablation of Millimeter-Wave Subwavelength Structures on Alumina and Sapphire

Picosecond Laser Ablation of Millimeter-Wave Subwavelength Structures on Alumina and Sapphire

Probing primordial gravitational waves: Ali CMB Polarization Telescope

Detecting Primordial Gravitational Waves: a forecast study on optimizing frequency distribution of next generation ground-based CMB telescope

Contact Info

Product

Resources

About