Irna Farikhah Department of Physics, Faculty of Mathematics and Natural Sciences-Gadjah Mada University
Sekip Utara, BLS 21, Bulaksumur, Yogyakarta 55281, Indonesia Indonesia
Yusril Yusuf Department of Physics, Faculty of Mathematics and Natural Sciences-IKIP PGRI Semarang
Sidodadi Timur 24, Semarang 55125, Indonesia Indonesia