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M. Hussain

Publications and source records attributed to M. Hussain.

4 recordsLinked to original sources

Deuteron-induced reactions on natural Zr from threshold to 50 MeV: production of $^{86}$Y

Two stacks of thin Zr foils were irradiated with 30 and 50 MeV deuterons, respectively, using the Lawrence Berkeley National Laboratory $88$-Inch Cyclotron, to investigate this production pathway for the promising PET tracer $^{86}$Y. Nineteen excitation functions for $^{\text{nat}}$Zr($d$,$x$) reactions were measured over a beam energy range of $6.3$--$47.64$ MeV, where the independent cross sections for $^{\text{nat}}$Zr($d$,$x$)$^{88}$Nb and $^\text{{nat}}$Zr($d$,$x$)$^{86\text{m, g}}$Y were measured for the first time. The well-characterized $^{\text{nat}}$Fe($d$,$x$)$^{56}$Co, $^{\text{nat}}$Ni($d$,$x$)$^{56}$Co, $^{\text{nat}}$Ni($d$,$x$)$^{58}$Co, $^{\text{nat}}$Ni($d$,$x$)$^{61}$Cu, $^{\text{nat}}$Ti($d$,$x$)$^{46}$Sc and $^{\text{nat}}$Ti($d$,$x$)$^{48}$V monitor reactions were used to determine the deuteron beam current throughout the stacks. All cross sections were determined using High Purity Germanium (HPGe) detector $\gamma$-ray spectroscopy. A variance minimization technique was employed to simultaneously constrain the deuteron beam currents with multiple monitor reactions, thus reducing systematic uncertainties. An additional $16$ channels are reported for reactions on the nickel, titanium, and iron monitor foils, leading to a total of $35$ excitation functions, with $7$ reaction channels reported for the first time in this work. The measured excitation functions are compared to calculations provided by the reaction modeling codes $\textsc{TALYS}-2.0$, $\textsc{ALICE}-2020$, $\textsc{CoH}-3.5.3$ and $\textsc{EMPIRE}-3.2.3$, as well as the $\textsc{TENDL}-2023$ data library. The degree of agreement between theory and experiments is discussed. The physical yields for $^{\text{nat}}$Zr($d$,$x$)$^{86}$Y and other yttrium isotopes produced are calculated and compared to other production pathways.

nucl-ex

Shake-off in XFEL heated solid density plasma

In atoms undergoing ionisation, an abrupt re-arrangement of free and bound electrons can lead to the ejection of another bound electron (shake-off). The spectroscopic signatures of shake-off have been predicted and observed in atoms and solids. Here, we present the first observation of this process in a solid-density plasma heated by an x-ray free electron laser. The results show that shake-off of L-shell electrons persists up to temperatures of 10 eV at solid density, and follow the probability predicted for solids. This work shows that shake-off should be included in plasma models for the correct interpretation of emission spectra.

physics.plasm-ph

Spectral control of high order harmonics through non-linear propagation effects

High harmonic generation (HHG) in crystals has revealed a wealth of perspectives such as all-optical mapping of the electronic band structure, ultrafast quantum information and the creation of novel all-solid-state attosecond sources. Significant efforts have been made to understand the microscopic aspects of HHG in crystals, whereas the macroscopic effects, such as non-linear propagation effects of the driving pulse inside the dense solid media and its impact on the HHG process is often overlooked. In this work, we study macroscopic effects by comparing two materials with distinct optical properties, silicon (Si) and zinc oxide (ZnO). By scanning the focal position of 85 fs, 2.123 $μ$m wavelength pulses inside the crystals (Z-scan) we reveal spectral shifts in the generated harmonics. We interpret the overall blueshift of the emitted harmonic spectrum as an imprint of the driving field spectral modulation occurring during the propagation inside the crystal. This is supported with numerical simulations. This study demonstrates that through manipulation of the fundamental driving field through non-linear propagation effects, precise control of the emitted HHG spectrum in solids can be realised. This method could offer a robust way to tailor HHG spectra for a range of spectroscopic applications.

physics.optics

Studies of the UHECR propagation in the Galactic Magnetic Field

We present the results of simulations of the ultra-high energy cosmic ray (UHECR) propagation in the Galactic magnetic field (GMF). Different assumptions on the large-scale GMF structure and/or primary particle lead to distinctly different deflection patterns of the highest energy cosmic rays (CR). The GMF modifies the exposure of an UHECR experiment to the extragalactic sky. We estimated these effects for the Pierre Auger experiment. Further forward-tracking studies under plausible UHECR sources scenarios will allow for direct comparison with the observed correlation between the nearby active galactic nuclei (AGN) and the highest energy Auger events.

astro-ph.HE