Short timescale behavior of colliding heavy nuclei at intermediate energies

An Antisymmetrized Molecular Dynamics model is used to explore the collision of $^{114}$Cd projectiles with $^{92}$Mo target nuclei at E/A=50 MeV over a broad range in impact parameter. The atomic number (Z), velocity, and emission pattern of the reaction products are examined as a function of the impact parameter and the cluster recognition time. The non-central collisions are found to be essentially binary in character resulting in the formation of an excited projectile-like fragment (PLF$^*$) and target-like fragment (TLF$^*$). The decay of these fragments occurs on a short timescale, 100$\le$t$\le$300 fm/c. The average excitation energy deduced for the PLF$^*$ and TLF$^*$ `saturates for mid-central collisions, 3.5$\le$b$\le$6 fm, with its magnitude depending on the cluster recognition time. For short cluster recognition times (t=150 fm/c), an average excitation energy as high as $\approx$6 MeV is predicted. Short timescale emission leads to a loss of initial correlations and results in features such as an anisotropic emission pattern of both IMFs and alpha particles emitted from the PLF$^*$ and TLF$^*$ in peripheral collisions.Comment: 19 pages, 17 figure

Timescale for equilibration of N/Z gradients in dinuclear systems

Equilibration of N/Z in binary breakup of an excited and transiently deformed projectile-like fragment (PLF*), produced in peripheral collisions of 64Zn + 27Al, 64Zn, 209Bi at E/A = 45 MeV, is examined. The composition of emitted light fragments (3<=Z<=6) changes with the decay angle of the PLF*. The most neutron-rich fragments observed are associated with a small rotation angle. A clear target dependence is observed with the largest initial N/Z correlated with the heavy, neutron-rich target. Using the rotation angle as a clock, we deduce that N/Z equilibration persists for times as long as 3-4 zs (1zs = 1 x 10^-21 s = 300 fm/c). The rate of N/Z equilibration is found to depend on the initial neutron gradient within the PLF*.Comment: 6 pages, 4 figure

Pengembangan Metode Block Matching Untuk Deteksi Copy-move Pada Pemalsuan Citra

Pemalsuan citra dengan maksud menutupi sebagian objek pada citra dengan blok lain pada citra yang sama disebut dengan copy-move. Deteksi copy-move pada citra dapat dilakukan pada domain spasial melalui pengolahan pada tiap pikselnya maupun pada domain frekeunsi melalui beberapa fungsi transformasi. Penelitian ini mengusulkan deteksi copy-move pada domain spasial dengan mengembangkan metode block macthing. Metode yang diusulkan terbagi atas dua pendekatan yaitu excact match dan robust match. Pendekatan excact match dimulai dengan: input citra RGB, pengambi-lan blok, penghitungan nilai hash tiap blok, pencarian blok yang mirip dan diakhiri dengan dengan operasi morfologi untuk penghalusan hasil deteksi. Sedangkan pendekatan robust match mirip dengan exact match namun nilai hash diganti dengan Discrete Cosine Transform (DCT). Hasil uji coba menujukkan bahwa pendekatan robust match mendapatkan hasil sedikit lebih baik dibandingkan dengan excact match dimana nilai rata-rata kualitas deteksi 75% dengan kualitas deteksi terbaik sebesar 97%

Enhanced dynamics in fusion of neutron-rich oxygen nuclei at above-barrier energies

Above-barrier fusion cross-sections for an isotopic chain of oxygen isotopes with A=16-19 incident on a $^{12}$C target are presented. Experimental data are compared with both static and dynamical microscopic calculations. These calculations are unable to explain the $\sim$37\% increase in the average above-barrier fusion cross-section observed for $^{19}$O as compared to $\beta$-stable oxygen isotopes. This result suggests that for neutron-rich nuclei existing time-dependent Hartree-Fock calculations underpredict the role of dynamics at near-barrier energies. High-quality measurement of above-barrier fusion for an isotopic chain of increasingly neutron-rich nuclei provides an effective means to probe this fusion dynamics.Comment: 6 pages, 4 figure