P. M. Walker - University of Strathclyde, Glasgow

P. M. Walker
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P. M. Walker
University of Strathclyde, Glasgow
United Kingdom

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Nuclear Theory (18)
Nuclear Experiment (17)
Physics - Mesoscopic Systems and Quantum Hall Effect (11)
General Relativity and Quantum Cosmology (8)
Physics - Optics (4)
Physics - Strongly Correlated Electrons (3)
High Energy Physics - Experiment (2)
Physics - Atomic Physics (2)
Nonlinear Sciences - Pattern Formation and Solitons (2)
Physics - Instrumentation and Detectors (2)
Nonlinear Sciences - Chaotic Dynamics (1)
High Energy Physics - Phenomenology (1)
High Energy Physics - Theory (1)
High Energy Astrophysical Phenomena (1)
Physics - Materials Science (1)

Publications Authored By P. M. Walker

We study exciton-polaritons in a two-dimensional Lieb lattice of micropillars. The energy spectrum of the system features two flat bands formed from $S$ and $P_{x,y}$ photonic orbitals, into which we trigger bosonic condensation under high power excitation. The symmetry of the orbital wave functions combined with photonic spin-orbit coupling gives rise to emission patterns with pseudospin texture in the flat band condensates. Read More

The quenching of the experimental spectroscopic factor for proton emission from the short-lived $d_{3/2}$ isomeric state in $^{151m}$Lu was a long-standing problem. In the present work, proton emission from this isomer has been reinvestigated in an experiment at the Accelerator Laboratory of the University of Jyv\"{a}skyl\"{a}. The proton-decay energy and half-life of this isomer were measured to be 1295(5) keV and 15. Read More

We study exciton-polariton nonlinear optical fluids in a high momentum regime for the first time. Defects in the fluid develop into dark solitons whose healing length decreases with increasing density. We deduce interaction constants for continuous wave polaritons an order of magnitude larger than with picosecond pulses. Read More

We report on the formation of a diverse family of transverse spatial polygon patterns in a microcavity polariton fluid under coherent driving by a blue-detuned pump. Patterns emerge spontaneously as a result of energy-degenerate polariton-polariton scattering from the pump state to interfering high order vortex and antivortex modes, breaking azimuthal symmetry. The interplay between a multimode parametric instability and intrinsic optical bistability leads to a sharp spike in the value of second order coherence $g^{(2)}(0)$, which we attribute to the strongly superlinear kinetics of the underlying scattering processes driving the formation of patterns. Read More

Excited states in neutron-rich nuclei located south-east of $^{132}$Sn are investigated by shell-model calculations. A new shell-model Hamiltonian is constructed for the present study. The proton-proton and neutron-neutron interactions of the Hamiltonian are obtained through the existing CD-Bonn $G$ matrix results, while the proton-neutron interaction across two major shells is derived from the monopole based universal interaction plus the M3Y spin-orbit force. Read More

We have identified a mechanism of collective nuclear de-excitation in a Bose-Einstein condensate of $^{135}$Cs atoms in their isomeric states, $^{135m}$Cs, suitable for the generation of coherent gamma photons. The process described here does not correspond to single-pass amplification, which cannot occur in atomic systems due to the large shift between absorption and emission lines, nor does it require the large densities associated to standard Dicke super-radiance. It thus overcome the limitations that have been hindering the generation of coherent gamma rays in many systems. Read More

Monolayers of molybdenum and tungsten dichalcogenides are direct bandgap semiconductors, which makes them promising for opto-electronic applications. In particular, van der Waals heterostructures consisting of monolayers of MoS2 sandwiched between atomically thin hexagonal boron nitride (hBN) and graphene electrodes allows one to obtain light emitting quantum wells (LEQWs) with low-temperature external quantum efficiency (EQE) of 1%. However, the EQE of MoS2 and MoSe2-based LEQWs shows behavior common for many other materials: it decreases fast from cryogenic conditions to room temperature, undermining their practical applications. Read More

The instantaneous luminosity of the Large Hadron Collider at CERN will be increased up to a factor of five with respect to the present design value by undergoing an extensive upgrade program over the coming decade. The most important upgrade project for the ATLAS Muon System is the replacement of the present first station in the forward regions with the so-called New Small Wheels (NSWs). The NSWs will be installed during the LHC long shutdown in 2018/19. Read More

A $^{238}$U projectile beam was used to create cadmium isotopes via abrasion-fission at 410 MeV/u in a beryllium target at the entrance of the in-flight separator FRS at GSI. The fission fragments were separated with the FRS and injected into the isochronous storage ring ESR for mass measurements. The Isochronous Mass Spectrometry (IMS) was performed under two different experimental conditions, with and without B$\rho$-tagging at the dispersive central focal plane of the FRS. Read More

We report an extended family of spin textures in coexisting modes of zero-dimensional polariton condensates spatially confined in tunable open microcavity structures. The coupling between photon spin and angular momentum, which is enhanced in the open cavity structures, leads to new eigenstates of the polariton condensates carrying quantised spin vortices. Depending on the strength and anisotropy of the cavity confinement potential and the strength of the spin-orbit coupling, which can be tuned via the excitonic/photonic fractions, the condensate emissions exhibit either spin-vortex-like patterns or linear polarization, in good agreement with theoretical modelling. Read More

New functionalities in nonlinear optics will require systems with giant optical nonlinearity as well as compatibility with photonic circuit fabrication techniques. Here we introduce a new platform based on strong light-matter coupling between waveguide photons and quantum-well excitons. On a sub-millimeter length scale we generate sub-picosecond bright temporal solitons at a pulse energy of only 0. Read More

Quasi-two-dimensional (2D) films of layered metal-chalcogenides have attractive optoelectronic properties. However, photonic applications of thin films may be limited owing to weak light absorption and surface effects leading to reduced quantum yield. Integration of 2D films in optical microcavities will permit these limitations to be overcome owing to modified light coupling with the films. Read More

This paper reports NMR measurements of the magnetic dipole moments of two high-K isomers, the 37/2$^-$, 51.4 m, 2740 keV state in $^{\rm 177}$Hf and the 8$^-$, 5.5 h, 1142 keV state in $^{\rm 180}$Hf by the method of on-line nuclear orientation. Read More

For the first time, a wide range of collective magnetic g-factors g$_{\rm R}$, obtained from a novel analysis of experimental data for multi-quasiparticle configurations in high-K isomers, is shown to exhibit a striking systematic variation with the relative number of proton and neutron quasiparticles, N$_{\rm p}$ - N$_{\rm n}$. Using the principle of additivity, the quasi-particle contribution to magnetism in high-K isomers of Lu - Re, Z = 71 - 75, has been estimated. Based on these estimates, band-structure branching ratio data are used to explore the behaviour of the collective contribution as the number and proton/neutron nature (N$_{\rm p}$, N$_{\rm n}$), of the quasi-particle excitations, change. Read More

We present a method to implement 3-dimensional polariton confinement with in-situ spectral tuning of the cavity mode. Our tunable microcavity is a hybrid system consisting of a bottom semiconductor distributed Bragg reflector (DBR) with a cavity containing quantum wells (QWs) grown on top and a dielectric concave DBR separated by a micrometer sized gap. Nanopositioners allow independent positioning of the two mirrors and the cavity mode energy can be tuned by controlling the distance between them. Read More

In the last two decades a number of nuclear structure and astrophysics experiments were performed at heavy-ion storage rings employing unique experimental conditions offered by such machines. Furthermore, building on the experience gained at the two facilities presently in operation, several new storage ring projects were launched worldwide. This contribution is intended to provide a brief review of the fast growing field of nuclear structure and astrophysics research at storage rings. Read More

Long-lived isomers in 212Bi have been studied following 238U projectile fragmentation at 670 MeV per nucleon. The fragmentation products were injected as highly charged ions into the GSI storage ring, giving access to masses and half-lives. While the excitation energy of the first isomer of 212Bi was confirmed, the second isomer was observed at 1478(30) keV, in contrast to the previously accepted value of >1910 keV. Read More

Total Routhian surface calculations have been performed to investigate rapidly rotating transfermium nuclei, the heaviest nuclei accessible by detailed spectroscopy experiments. The observed fast alignment in $^{252}$No and slow alignment in $^{254}$No are well reproduced by the calculations incorporating high-order deformations. The different rotational behaviors of $^{252}$No and $^{254}$No can be understood for the first time in terms of $\beta_6$ deformation that decreases the energies of the $\nu j_{15/2}$ intruder orbitals below the N=152 gap. Read More

Authors: S. Akkoyun, A. Algora, B. Alikhani, F. Ameil, G. de Angelis, L. Arnold, A. Astier, A. Ataç, Y. Aubert, C. Aufranc, A. Austin, S. Aydin, F. Azaiez, S. Badoer, D. L. Balabanski, D. Barrientos, G. Baulieu, R. Baumann, D. Bazzacco, F. A. Beck, T. Beck, P. Bednarczyk, M. Bellato, M. A. Bentley, G. Benzoni, R. Berthier, L. Berti, R. Beunard, G. Lo Bianco, B. Birkenbach, P. G. Bizzeti, A. M. Bizzeti-Sona, F. Le Blanc, J. M. Blasco, N. Blasi, D. Bloor, C. Boiano, M. Borsato, D. Bortolato, A. J. Boston, H. C. Boston, P. Bourgault, P. Boutachkov, A. Bouty, A. Bracco, S. Brambilla, I. P. Brawn, A. Brondi, S. Broussard, B. Bruyneel, D. Bucurescu, I. Burrows, A. Bürger, S. Cabaret, B. Cahan, E. Calore, F. Camera, A. Capsoni, F. Carrió, G. Casati, M. Castoldi, B. Cederwall, J. -L. Cercus, V. Chambert, M. El Chambit, R. Chapman, L. Charles, J. Chavas, E. Clément, P. Cocconi, S. Coelli, P. J. Coleman-Smith, A. Colombo, S. Colosimo, C. Commeaux, D. Conventi, R. J. Cooper, A. Corsi, A. Cortesi, L. Costa, F. C. L. Crespi, J. R. Cresswell, D. M. Cullen, D. Curien, A. Czermak, D. Delbourg, R. Depalo, T. Descombes, P. Désesquelles, P. Detistov, C. Diarra, F. Didierjean, M. R. Dimmock, Q. T. Doan, C. Domingo-Pardo, M. Doncel, F. Dorangeville, N. Dosme, Y. Drouen, G. Duchêne, B. Dulny, J. Eberth, P. Edelbruck, J. Egea, T. Engert, M. N. Erduran, S. Ertürk, C. Fanin, S. Fantinel, E. Farnea, T. Faul, M. Filliger, F. Filmer, Ch. Finck, G. de France, A. Gadea, W. Gast, A. Geraci, J. Gerl, R. Gernhäuser, A. Giannatiempo, A. Giaz, L. Gibelin, A. Givechev, N. Goel, V. González, A. Gottardo, X. Grave, J. Grȩbosz, R. Griffiths, A. N. Grint, P. Gros, L. Guevara, M. Gulmini, A. Görgen, H. T. M. Ha, T. Habermann, L. J. Harkness, H. Harroch, K. Hauschild, C. He, A. Hernández-Prieto, B. Hervieu, H. Hess, T. Hüyük, E. Ince, R. Isocrate, G. Jaworski, A. Johnson, J. Jolie, P. Jones, B. Jonson, P. Joshi, D. S. Judson, A. Jungclaus, M. Kaci, N. Karkour, M. Karolak, A. Kaşkaş, M. Kebbiri, R. S. Kempley, A. Khaplanov, S. Klupp, M. Kogimtzis, I. Kojouharov, A. Korichi, W. Korten, Th. Kröll, R. Krücken, N. Kurz, B. Y. Ky, M. Labiche, X. Lafay, L. Lavergne, I. H. Lazarus, S. Leboutelier, F. Lefebvre, E. Legay, L. Legeard, F. Lelli, S. M. Lenzi, S. Leoni, A. Lermitage, D. Lersch, J. Leske, S. C. Letts, S. Lhenoret, R. M. Lieder, D. Linget, J. Ljungvall, A. Lopez-Martens, A. Lotodé, S. Lunardi, A. Maj, J. van der Marel, Y. Mariette, N. Marginean, R. Marginean, G. Maron, A. R. Mather, W. Mȩczyński, V. Mendéz, P. Medina, B. Melon, R. Menegazzo, D. Mengoni, E. Merchan, L. Mihailescu, C. Michelagnoli, J. Mierzejewski, L. Milechina, B. Million, K. Mitev, P. Molini, D. Montanari, S. Moon, F. Morbiducci, R. Moro, P. S. Morrall, O. Möller, A. Nannini, D. R. Napoli, L. Nelson, M. Nespolo, V. L. Ngo, M. Nicoletto, R. Nicolini, Y. Le Noa, P. J. Nolan, M. Norman, J. Nyberg, A. Obertelli, A. Olariu, R. Orlandi, D. C. Oxley, C. Özben, M. Ozille, C. Oziol, E. Pachoud, M. Palacz, J. Palin, J. Pancin, C. Parisel, P. Pariset, G. Pascovici, R. Peghin, L. Pellegri, A. Perego, S. Perrier, M. Petcu, P. Petkov, C. Petrache, E. Pierre, N. Pietralla, S. Pietri, M. Pignanelli, I. Piqueras, Z. Podolyak, P. Le Pouhalec, J. Pouthas, D. Pugnére, V. F. E. Pucknell, A. Pullia, B. Quintana, R. Raine, G. Rainovski, L. Ramina, G. Rampazzo, G. La Rana, M. Rebeschini, F. Recchia, N. Redon, M. Reese, P. Reiter, P. H. Regan, S. Riboldi, M. Richer, M. Rigato, S. Rigby, G. Ripamonti, A. P. Robinson, J. Robin, J. Roccaz, J. -A. Ropert, B. Rossé, C. Rossi Alvarez, D. Rosso, B. Rubio, D. Rudolph, F. Saillant, E. Şahin, F. Salomon, M. -D. Salsac, J. Salt, G. Salvato, J. Sampson, E. Sanchis, C. Santos, H. Schaffner, M. Schlarb, D. P. Scraggs, D. Seddon, M. Şenyiğit, M. -H. Sigward, G. Simpson, J. Simpson, M. Slee, J. F. Smith, P. Sona, B. Sowicki, P. Spolaore, C. Stahl, T. Stanios, E. Stefanova, O. Stézowski, J. Strachan, G. Suliman, P. -A. Söderström, J. L. Tain, S. Tanguy, S. Tashenov, Ch. Theisen, J. Thornhill, F. Tomasi, N. Toniolo, R. Touzery, B. Travers, A. Triossi, M. Tripon, K. M. M. Tun-Lanoë, M. Turcato, C. Unsworth, C. A. Ur, J. J. Valiente-Dobon, V. Vandone, E. Vardaci, R. Venturelli, F. Veronese, Ch. Veyssiere, E. Viscione, R. Wadsworth, P. M. Walker, N. Warr, C. Weber, D. Weisshaar, D. Wells, O. Wieland, A. Wiens, G. Wittwer, H. J. Wollersheim, F. Zocca, N. V. Zamfir, M. Ziȩbliński, A. Zucchiatti

The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation gamma-ray spectrometer. AGATA is based on the technique of gamma-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a gamma ray deposits its energy within the detector volume. Read More

The low-lying states in 106Zr and 108Zr have been investigated by means of {\beta}-{\gamma} and isomer spectroscopy at the RI beam factory, respectively. A new isomer with a half-life of 620\pm150 ns has been identified in 108Zr. For the sequence of even-even Zr isotopes, the excitation energies of the first 2+ states reach a minimum at N = 64 and gradually increase as the neutron number increases up to N = 68, suggesting a deformed sub-shell closure at N = 64. Read More

We investigate the influence of deformation on the possible occurrence of long-lived $K$ isomers in Hf isotopes around N=116, using configuration-constrained calculations of potential-energy surfaces. Despite having reduced shape elongation, the multi-quasiparticle states in $^{186,188}$Hf remain moderately robust against triaxial distortion, supporting the long expected occurrence of exceptionally long-lived isomers. The calculations are compared with available experimental data. Read More

Using, for the first time, configuration-constrained potential-energy-surface calculations with the inclusion of $\beta_6$ deformation, we find remarkable effects of the high order deformation on the high-$K$ isomers in $^{254}$No, the focus of recent spectroscopy experiments on superheavy nuclei. For shapes with multipolarity six, the isomers are more tightly bound and, microscopically, have enhanced deformed shell gaps at $N=152$ and $Z=100$. The inclusion of $\beta_6$ deformation significantly improves the description of the very heavy high-$K$ isomers. Read More

We use the semi-classical approximation in perturbative scalar quantum electrodynamics to calculate the quantum correction to the Larmor radiation formula to first order in Planck's constant in the non-relativistic approximation, choosing the initial state of the charged particle to be a momentum eigenstate. We calculate this correction in two cases: in the first case the charged particle is accelerated by a time-dependent but space-independent vector potential whereas in the second case it is accelerated by a time-independent vector potential which is a function of one spatial coordinate. We find that the corrections in these two cases are different even for a charged particle with the same classical motion. Read More

We investigate the physics of a charged scalar particle moving in conformally flat spacetime with the conformal factor depending only on time in the framework of quantum electrodynamics (QED). In particular, we show that the radiation-reaction force derived from QED agrees with the classical counterpart in the limit $\hbar \to 0$ using the fact that to lowest order in $\hbar$ the charged scalar field theory with mass $m$ in conformally flat spacetime with conformal factor $\Omega(t)$, which we call Model B, is equivalent to that in flat spacetime with a time-dependent mass $m\Omega(t)$, which we call Model A, at tree level in this limit. We also consider the one-loop QED corrections to these two models in the semi-classical approximation. Read More

A shape phase transition is demonstrated to occur in 190W by applying the Projected Shell Model, which goes beyond the usual mean-field approximation. Rotation alignment of neutrons in the high-j, i_{13/2} orbital drives the yrast sequence of the system, changing suddenly from prolate to oblate shape at angular momentum 10$\hbar$. We propose observables to test the picture. Read More

The projected shell model is used to study the multi-quasiparticle and collective excitations of 178Hf. With an axially symmetric basis, the spin-16 isomer at 2.4 MeV appears to be well separated in energy/spin space from other configurations. Read More

Configuration-constrained calculations of potential-energy surfaces in even-even superheavy nuclei reveal systematically the existence at low excitation energies of multi-quasiparticle states with deformed axially symmetric shapes and large angular momenta. These results indicate the prevalence of long-lived, multi-quasiparticle isomers. In a quantal system, the ground state is usually more stable than the excited states. Read More

With the self-consistent three-dimensional cranked Hartree-Fock-Bogoliubov (3d-cranked HFB) method, various types of rotational motion near the yrast line are investigated in an even-even nucleus in the $A\simeq 130$ mass region ($^{134}_{58}$Ce$_{76}$). The possibilities of chiral rotations, tilted-rotations, and dynamical aspects of these rotations are discussed through the analysis of the 3d-cranked HFB solutions. Although a stable planar solution of the chiral rotation is obtained, an aplanar chiral configuration is found to be unstable when triaxial deformation is treated self-consistently. Read More

We report a solution of the tilted-axis cranked HFB equation for $^{164}$Hf, which shows wobbling motion coupled to gamma vibration at high spin ($J\simeq 60\hbar$). Possible anharmonicity and splitting of energy levels are also discussed as a consequence of the wobbling motion with large amplitude. Read More

A self-consistent and quantal description of high-$K$ bands is given in the framework of the tilted-axis cranking model. (With a $\theta=90^{\circ}$ tilt angle with respect to $x$-axis, this cranking model is equivalent to the $z$-axis cranking.) The numerical results of the HFB calculations in this framework are compared with experimental data for two quasi-particle excited bands with $K^{\pi}=6^+$ in $^{178}$W. Read More

We analyze a mechanism of coupling of high- and low-$K$ bands in terms of a dynamical treatment for nuclear rotations, i.e.,wobbling motion. Read More

We have performed tilted-axis-cranked Hartree-Fock-Bogoliubov calculations for a neutron-rich hafnium isotope ($^{182}$Hf) whose proton and neutron numbers are both in the upper shell region. We study whether the shell effects play a role in producing high-$K$ isomers or highly gamma-deformed states at high spin. In particular, the possibility of shape coexistence and the effect of wobbling motion are discussed. Read More

Tilted-axis cranking calculations have been performed for multi-quasiparticle states in well deformed A$\approx$180 nuclei. In the limit of zero pairing, not only are the calculated moments of inertia substantially smaller than for rigid rotation, but also they are close to the experimental values. The moments of inertia are found to be insensitive to dynamic pair correlations. Read More

The Beyond the Standard Model Working Group discussed a variety of topics relating to exotic searches at current and future colliders, and the phenomenology of current models beyond the Standard Model. For example, various supersymmetric (SUSY) and extra dimensions search possibilities and constraints are presented. Fine-tuning implications of SUSY searches are derived. Read More

We develop a semiclassical theory for the spectral rigidity of non-hydrogenic Rydberg atoms in electric fields and evaluate the significant deviations from the well-known Poissonian behaviour in the hydrogenic case. The resulting formula is shown to be in excellent agreement with the exact quantal result. We also investigate diamagnetic atoms; we find that, in contrast to the classically integrable atoms, diffraction has a small effect on the spectral rigidity in the classically chaotic atom. Read More

Nuclear shapes and odd-nucleon blockings strongly influence the odd-even differences of nuclear masses. When such effects are taken into account, the determination of the pairing strength is modified resulting in larger pair gaps. The modified pairing strength leads to an improved self-consistent description of moments of inertia and backbending frequencies, with no additional parameters. Read More

We discuss some recent results on the statistics of the Coulomb Blockade in disordered quantum dots containing spinless interacting fermions using the self-consistent Hartree-Fock approximation. We concentrate on the regime r_s >~1, with finite dimensionless conductance g. We present significantly different results for the cases of a Coulomb and a nearest-neighbour bare interaction. Read More

We investigate the addition spectrum of disordered quantum dots containing spinless interacting fermions using the self-consistent Hartree-Fock approximation. We concentrate on the regime r_s >~1, with finite dimensionless conductance g. We find that in this approximation the peak spacing fluctuations do not scale with the mean single particle level spacing for either Coulomb or nearest neighbour interactions when r_s >~1. Read More

We analyse the ground state of spinless fermions on a lattice in a weakly disordered potential, interacting via a nearest neighbour interaction, by applying the self-consistent Hartree-Fock approximation. We find that charge density modulations emerge progressively when r_s >1, even away from half-filling, with only short-range density correlations. Classical geometry dependent "magic numbers" can show up in the addition spectrum which are remarkably robust against quantum fluctuations and disorder averaging. Read More

We present a series of test beds for numerical codes designed to find apparent horizons. We consider three apparent horizon finders that use different numerical methods: one of them in axisymmetry, and two fully three-dimensional. We concentrate first on a toy model that has a simple horizon structure, and then go on to study single and multiple black hole data sets. Read More

We present techniques and methods for analyzing the dynamics of event horizons in numerically constructed spacetimes. There are three classes of analytical tools we have investigated. The first class consists of proper geometrical measures of the horizon which allow us comparison with perturbation theory and powerful global theorems. Read More

We discuss a successful three-dimensional cartesian implementation of the Bona-Mass\'o hyperbolic formulation of the 3+1 Einstein evolution equations in numerical relativity. The numerical code, which we call ``Cactus,'' provides a general framework for 3D numerical relativity, and can include various formulations of the evolution equations, initial data sets, and analysis modules. We show important code tests, including dynamically sliced flat space, wave spacetimes, and black hole spacetimes. Read More

We report new results which establish that the accurate 3-dimensional numerical simulation of generic single-black-hole spacetimes has been achieved by characteristic evolution with unlimited long term stability. Our results cover a selection of distorted, moving and spinning single black holes, with evolution times up to 60,000M. Read More

We describe a grid generation procedure designed to construct new classes of orthogonal coordinate systems for binary black hole spacetimes. The computed coordinates offer an alternative approach to current methods, in addition to providing a framework for potentially more stable and accurate evolutions of colliding black holes. As a particular example, we apply our procedure to generate appropriate numerical grids to evolve Misner's axisymmetric initial data set representing two equal mass black holes colliding head-on. Read More

Binary black hole interactions provide potentially the strongest source of gravitational radiation for detectors currently under development. We present some results from the Binary Black Hole Grand Challenge Alliance three- dimensional Cauchy evolution module. These constitute essential steps towards modeling such interactions and predicting gravitational radiation waveforms. Read More

We describe a numerical grid generating procedure to construct new classes of orthogonal coordinate systems that are specially adapted to binary black hole spacetimes. The new coordinates offer an alternative approach to the conventional \v{C}ade\v{z} coordinates, in addition to providing a potentially more stable and flexible platform to extend previous calculations of binary black hole collisions. Read More