CHARACTERIZATON OF A HOLLOW-CATHODE LAMP TO MEASURE ACCURATE TRANSITION PROBABILITIES OF RARE EARTH ELEMENTS P. R. Sen Sarma, M. T. Belmonte, S. Mar , N. Lorenzana Universidad de Valladolid, Department of Theoretical and Atomic Physics and Optics, Paseo de Belén 7,47011 Valladolid, Spain. WHAT DO WE DO AND HOW IS IT DONE? The quality and quantity of atomic data, like transition probabilities of rare-earths, is a major hindrance for astrophysicists to accurately calculate chemical abundances of stars[1]. Thus it is of utmost importance to produce new improved atomic data. Spectral Range: 200 nm to 800 nm Resolving Power: 150 000 at 450 nm ACKNOWLEDGEMENTS: P. R. Sen Sarma thanks the University of Valladolid for his PhD grant. M. T. Belmonte acknowledges the funding provided by the Spanish government through projects PID2021-127786NA-100 and a Beatriz Galindo Fellowship. PRATYUSH RANJAN SEN SARMA pratyushranjan.sen-sarma@uva.es MARIA TERESA BELMONTE SAINZ EZQUERRA mariateresa.belmonte@uva.es In order to report transition probabilities (Aki) of Nd III in the UV-visible range, we use a diffraction grating spectrometer (2400 lines/mm) to measure the branching fractions (BFi). Using this BFi and lifetimes (τk), Aki is calculated. VOLTAGE-CURRENT CHARACTERISTIC OF THE HOLLOW-CATHODE LAMP (HCL) STABILITY OF THE HCL OVER TIME We measure intensities of Ar II lines at different wavelengths for transitions from different upper energy levels over a period of almost two hours. Current and pressure are 300 mA and 150 Pa, respectively. To make sure that our Hollow-cathode Lamp is operating in the abnormal glow region of its discharge curve, the voltage-current characteristic is obtained for low pressures in order to get “nice spectroscopic property” [2]. The resistance of the lamp decreases with an increase in pressure due to the increase in Ar atoms. Wavelength (nm) Transition Probability (*108s-1) Upper Energy Level (eV) Intensity Variation 349.1 2.31 [3][4] 22.8 10% 423.72 0.112 [3][4] 21.4 7% 611.5 0.2 [3][5] 21.1 3% Hollow-Cathode lamp is operated in the abnormal glow region of the gas-discharge curve of Ar II. We have used standard Tungsten and Deuterium lamps to obtain the response function. We measure the same response using the branching ratio (BR) method [6]. This method takes the transmittance of the lamp’s front window into consideration. RESPONSE FUNCTION OF OUR SETUP REFERENCES [1] Banerjee, Smaranika, et al. ApJ 934.2 (2022): 117. [2] B. Barbieri, N. Beverini and A. Sasso, Rev. Mod. Phys. 62, 603 (1990). [3] Kramida, A., Ralchenko, Yu., Reader, J., and NIST ASD Team (2022). NIST Atomic Spectra Da- tabase (ver. 5.10), [Online]. Available: https://physics.nist.gov/asd [2023, June 21]. National Insti- tute of Standards and Technology, Gaithersburg, MD. DOI: https://doi.org/10.18434/T4W30F [4] W. R. Bennett, Jr., P. J. Kindlmann, and G. N. Mercer, in Chemical Lasers: Applied Optics Supplement 2, 34 (Edited by J. N. Howard, Opt. Soc. America, 1965) [5] R. Schnapauff, Z. Astrophys. 68, 431 (1968) (Ger.) [6] Whaling, W., M. T. Carle, and M. L. Pitt. JQSRT 50.1 (1993): 7-18. [6] Ical : Calibrated Intensity; Imeasured : measured Intensity Ɛ(λ) : Response function of the setup at wavelength λ