| 1. |
- Petri, M., et al.
(författare)
-
Structure of C-16: Testing shell model and ab initio approaches
- 2012
-
Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 86:4, s. Art. no. 044329-
-
Tidskriftsartikel (refereegranskat)abstract
- Excited states in C-16 were populated via the Be-9(N-17,C-16+gamma)X one-proton knockout reaction. The lifetime of the 2(1)(+) state in C-16 was measured using the recoil distance method. The extracted lifetime of tau(+)(21) = 11.4(-0.9)(+0.8)(stat) +/- 0.7(syst(B rho))(-1.5)(+0.0)(syst(feeding)) ps yields a deduced B(E2;2(1)(+) -> 0(1)(+)) = 4.21(-0.26)(+0.34)(stat)(-0.24)(+0.28)(syst(B rho))(-0.00)(+0.64)(syst(feeding)) e(2)fm(4) value in good agreement with a previous measurement. The one-proton knockout cross section is used to extract the proton amplitude of the C-16 2(1)(+) state, which confirms the neutron dominant character of this state. Gamma-ray branching ratios between the 2(2)(+) state and the 2(1)(+) and ground states were also determined. The results are compared with p-sd shell model and no-core shell model (with NN and NN + NNN) calculations. The inclusion of three-body forces are essential in order for the no-core shell model calculations to reproduce the experimental findings on the gamma-ray branching ratios.
|
|
| 2. |
- Grigorenko, L. V., et al.
(författare)
-
Complete correlation studies of two-proton decays: Be-6 and Fe-45
- 2009
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 677:1-2, s. 30-35
-
Tidskriftsartikel (refereegranskat)abstract
- The complete three-body correlation pictures are experimentally reconstructed for the two-proton decays of the Be-6 and (45)e ground states. We are able to see qualitative similarities and differences between these decays. They demonstrate very good agreement with the predictions of a theoretical three-body cluster model. Validity of the theoretical methods for treatment of the three-body Coulombic decays of this class is thus established by the broad range of lifetimes and nuclear masses spanned by these cases. Implementations for decay dynamics and nuclear structure of 2p emitters are discussed. (C) 2009 Elsevier B.V. All rights reserved.
|
|
| 3. |
- Park, Joochun, et al.
(författare)
-
Toward the limit of nuclear binding on the N = Z line : Spectroscopy of Cd-96
- 2019
-
Ingår i: Physical Review C. - : AMER PHYSICAL SOC. - 2469-9985 .- 2469-9993. ; 99:2
-
Tidskriftsartikel (refereegranskat)abstract
- A gamma -decaying isomeric state (tau(1/2) = 197(-17)(+19) ns) has been identified in Cd-96, which is one alpha particle away from the last known bound N = Z nucleus, Sn-100. Comparison of the results with shell-model calculations has allowed a tentative experimental level scheme to be deduced and the isomer to be interpreted as a medium-spin negative-parity spin trap based on the coupling of isoscalar (T = 0) and isovector (T = 1) neutron-proton pairs. The data also suggest evidence for the population of a 9(+) T = 1 state, which is predicted by shell-model calculations to be yrast. Such a low-lying T = 1 state, which is unknown in lighter mass even-even self-conjugate nuclei, can also be interpreted in terms of the coupling of T = 0 and T = 1 neutron-proton pairs.
|
|
| 4. |
- Jigmeddorj, B., et al.
(författare)
-
New low-spin states of 122Xe observed via high-statistics beta-decay of 122Cs
- 2018
-
Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 178, s. 02026-02026
-
Tidskriftsartikel (refereegranskat)abstract
- Excited states of 122Xe were studied via the β+/EC decay of 122Cs with the 8π γ-ray spectrometer at the TRIUMF-ISAC facility. Compton-suppressed HPGe detectors were used for measurements of γ-ray intensities, γγ coincidences, and γ-γ angular correlations. Two sets of data were collected to optimize the decays of the ground (21.2 s) and isomeric (3.7 min) states of 122Cs. The data collected have enabled the observation of about 505 new transitions and about 250 new levels, including 51 new low-spin states. Spin assignments have been made for 58 low-spin states based on the deduced β-decay feeding and γ-γ angular correlation analyses.
|
|
| 5. |
- Fiorelli, R., et al.
(författare)
-
CMOS Front End for Interfacing Spin-Hall Nano-Oscillators for Neuromorphic Computing in the GHz Range
- 2023
-
Ingår i: Electronics. - : MDPI AG. - 2079-9292. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- Spin-Hall-effect nano-oscillators are promising beyond the CMOS devices currently available, and can potentially be used to emulate the functioning of neurons in computational neuromorphic systems. As they oscillate in the 4-20 GHz range, they could potentially be used for building highly accelerated neural hardware platforms. However, due to their extremely low signal level and high impedance at their output, as well as their microwave-range operating frequency, discerning whether the SHNO is oscillating or not carries a great challenge when its state read-out circuit is implemented using CMOS technologies. This paper presents the first CMOS front-end read-out circuitry, implemented in 180 nm, working at a SHNO oscillation frequency up to 4.7 GHz, managing to discern SHNO amplitudes of 100 mu V even for an impedance as large as 300 ohm and a noise figure of 5.3 dB(300 ohm). A design flow of this front end is presented, as well as the architecture of each of its blocks. The study of the low-noise amplifier is deepened for its intrinsic difficulties in the design, satisfying the characteristics of SHNOs.
|
|
| 6. |
- Kumar, Akash, et al.
(författare)
-
Robust Mutual Synchronization in Long Spin Hall Nano-oscillator Chains
- 2023
-
Ingår i: Nano Letters. - 1530-6984. ; 23:14, s. 6720-6726
-
Tidskriftsartikel (refereegranskat)abstract
- Mutual synchronizationof N serially connectedspintronic nano-oscillators boosts their coherence by N and peak power by N (2). Increasing thenumber of synchronized nano-oscillators in chains holds significancefor improved signal quality and emerging applications such as oscillatorbased unconventional computing. We successfully fabricate spin Hallnano-oscillator chains with up to 50 serially connected nanoconstrictionsusing W/NiFe, W/CoFeB/MgO, and NiFe/Pt stacks. Our experiments demonstraterobust and complete mutual synchronization of 21 nanoconstrictionsat an operating frequency of 10 GHz, achieving line widths 79,000. As the number of mutually synchronizedoscillators increases, we observe a quadratic increase in peak power,resulting in 400-fold higher peak power in long chains compared toindividual nanoconstrictions. While chains longer than 21 nanoconstrictionsalso achieve complete mutual synchronization, it is less robust, andtheir signal quality does not improve significantly, as they tendto break into partially synchronized states.
|
|
| 7. |
- Rajabali, M., et al.
(författare)
-
Experimental and molecular dynamics studies of an ultra-fast sequential hydrogen plasma process for fabricating phosphorene-based sensors
- 2021
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- Low concentration phosphorene-based sensors have been fabricated using a facile and ultra-fast process which is based on an exfoliation-free sequential hydrogen plasma treatment to convert the amorphous phosphorus thin film into mono- or few-layered phosphorene sheets. These sheets have been realized directly on silicon substrates followed by the fabrication of field-effect transistors showing the low leakage current and reasonable mobility for the nano-sensors. Being capable of covering the whole surface of the silicon substrate, red phosphorus (RP) coated substrate has been employed to achieve large area phosphorene sheets. Unlike the available techniques including mechanical exfoliation, there is no need for any exfoliation and/or transfer step which is significant progress in shortening the device fabrication procedure. These phosphorene sheets have been examined using transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Raman spectroscopy and atomic-force microscopy (AFM). Electrical output in different states of the crystallization as well as its correlation with the test parameters have been also extensively used to examine the evolution of the phosphorene sheets. By utilizing the fabricated devices, the sensitivity of the phosphorene based-field effect transistors to the soluble L-Cysteine in low concentrations has been studied by measuring the FET response to the different concentrations. At a gate voltage of − 2.5 V, the range of 0.07 to 0.60 mg/ml of the L-Cysteine has been distinguishably detected presenting a gate-controlled sensor for a low-concentration solution. A reactive molecular dynamics simulation has been also performed to track the details of this plasma-based crystallization. The obtained results showed that the imparted energy from hydrogen plasma resulted in a phase transition from a system containing red phosphorus atoms to the crystal one. Interestingly and according to the simulation results, there is a directional preference of crystal growth as the crystalline domains are being formed and RP atoms are more likely to re-locate in armchair than in zigzag direction.
|
|
| 8. |
- Kumar, Akash, et al.
(författare)
-
Fabrication of voltage-gated spin Hall nano-oscillators
- 2022
-
Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; :4, s. 1432-1439
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate an optimized fabrication process for electric field (voltage gate) controlled nano-constriction spin Hall nano-oscillators (SHNOs), achieving feature sizes of <30 nm with easy to handle ma-N 2401 e-beam lithography negative tone resist. For the nanoscopic voltage gates, we utilize a two-step tilted ion beam etching approach and through-hole encapsulation using 30 nm HfOx. The optimized tilted etching process reduces sidewalls by 75% compared to no tilting. Moreover, the HfOx encapsulation avoids any sidewall shunting and improves gate breakdown. Our experimental results on W/CoFeB/MgO/SiO2 SHNOs show significant frequency tunability (6 MHz V-1) even for moderate perpendicular magnetic anisotropy. Circular patterns with diameter of 45 nm are achieved with an aspect ratio better than 0.85 for 80% of the population. The optimized fabrication process allows incorporating a large number of individual gates to interface to SHNO arrays for unconventional computing and densely packed spintronic neural networks.
|
|
| 9. |
- Litvinenko, Artem, 1989, et al.
(författare)
-
Phase noise analysis of mutually synchronized spin Hall nano-oscillators
- 2023
-
Ingår i: APPLIED PHYSICS LETTERS. - 0003-6951. ; 122:22
-
Tidskriftsartikel (refereegranskat)abstract
- The reduction of phase noise in electronic systems is of utmost importance in modern communication and signal processing applications and requires an understanding of the underlying physical processes. Here, we systematically study the phase noise in mutually synchronized chains of nano-constriction spin Hall nano-oscillators (SHNOs). We find that longer chains have improved phase noise figures at low offset frequencies (1/f noise), where chains of two and ten mutually synchronized SHNOs have 2.8 and 6.2 dB lower phase noise than single SHNOs. This is close to the theoretical values of 3 and 10 dB, and the deviation is ascribed to process variations between nano-constrictions. However, at higher offset frequencies (thermal noise), the phase noise unexpectedly increases with chain length, which we ascribe to process variations, a higher operating temperature in the long chains at the same drive current and phase delays in the coupling between nano-constrictions.
|
|
