Measurement of Neutron Total Cross Sections of Natural Hafnium and Tantalum at Pohang Neutron Facility Course Title: Experimental Method and Data Process Respected Professor Kihyeon Cho Prepared By: A.K.M. Moinul Haque Meaze Student ID: Department of Physics Kyungpook National University Republic of Korea The 23rd March, Preparation For KPS Spring Meeting

We have measured neutron total cross sections of natural hafnium (Hf) and tantalum (Ta) in the neutron energy region from 0.1 eV to 100 eV by using the time of flight method at the Pohang Neutron Facility (PNF). The PNF consists of an 100 MeV electron linac, a water cooled Ta target, four position automatic sample changer controlled remotely by CAMAC data acquisition system, and a 6 LiZnS(Ag) glass scintillator as a neutron detector. The distances from the water cooled Ta target to the sample changer and to the scintillator are 5.4m and 10.8m respectively. Notch filter consists of Cobalt (Co), Indium (In) and Cadmium (Cd) which has a large resonance peaks in the spectrum to determine the background levels. To reduce gamma flash originated from the neutron target we have employed a neutron-gamma separation system based on their different pulse shape. Resonance parameters were determined with the computer code SAMMY which utilizes both Doppler and resolution broadening effects and Bayes' generalized least squares technique. The present total cross sections were compared with evaluated data in ENDF/B-VI.8 and the previous experimental data. The resonances parameters were compared with Landolt-Börstein’s data. ABSTRACT ABSTRACT The 23rd March, Preparation For KPS Spring Meeting

Information about the relative probabilities of different reactions provides clues to the problem of nuclear structure and offers a testing ground for ideas about nuclear forces. So cross section is used to obtain information about the internal structure of atomic nuclei and their constituents. The possibility of achieving a chain reaction and to design and development of a nuclear reactor depend strongly on the values of neutron cross section in the thermal energy region. So depending on the values of total neutron cross sections we may use the materials in the reactor. Name of the Sample Area (cm 2 ) Thickness, t (a/b) Atomic weight, A (amu) Density, ρ (g-cm -3 ) Atomic density, N (cm -2 ) Hafnium Tantalum 5x x x10 21 INTRODUCTIONINTRODUCTION CHARECTERISTICS OF SAMPLES USED IN THIS EXPERIMENT The 24rd March, Preparation For KPS Spring Meeting

10 Ta Plates - 3 (40 mm  x 2mm t) - 2 (40 mm  x 3mm t) - 1 (40 mm  x 4mm t) - 4 (40 mm  x 6mm t) with 2 mm t Ti cover Ta 161 ( ,n)Ta 160 Linac Target Moderator Size Moderator INSTROMENTSINSTROMENTS The 23rd March, Preparation For KPS Spring Meeting

INSTROMENTS(CONTINUED)INSTROMENTS(CONTINUED) The 23rd March, Preparation For KPS Spring Meeting Experimental Setup Outer side of TOF Sample Changer

USED EQUATIONS The 23rd March, Preparation For KPS Spring Meeting

ANALYZED DATA The 23rd March, Preparation For KPS Spring Meeting Background level determination with Co, In, and Cd samples. Hf In & Out with Background Ta In & Out with Background

LORENZIAN FITTINGS The 23rd March, Preparation For KPS Spring Meeting

Hf total cross section from TOF spectrum Hf USE NEW SPIN GROUP FORMAT chi squared is wanted do not suppress any intermediate results generate plot file atomically twenty broadening is wanted exponential folding transmission Ta total cross section from TOF spectrum Ta USE NEW SPIN GROUP FORMAT chi squared is wanted do not suppress any intermediate results generate plot file atomically twenty broadening is wanted exponential folding transmission LEAST SQUARE FITTING AND SAMMY INPut The 23rd March, Preparation For KPS Spring Meeting Least Square Fitting SAMMY Ta INPut SAMMY Hf INPut

RESULTS: TOTAL CROSS SECTIONS The 23rd March, Preparation For KPS Spring Meeting Measured Hf Total Cross Section

Hf Isotope JL E(eV)   (meV)  n (meV) Present ( 1)60.326( 2)2.3009( 3) Landolt-Börnstein Present (4) (5) ( 6) Landolt-Börnstein Present ( 7) ( 8)4.9547(9) Landolt-Börnstein Present (10) (11) (12) Landolt-Börnstein29.94(20) Present (13)60.3 (14) (15) Landolt-Börnstein70.5(3) Present (16)60.302( 17)64.925( 18) Landolt-Börnstein77.9(3) Hf IsotopeJl E(eV)   (meV)  n (meV) 17830Present (160)84.520(161)25.222(162) Landolt-Börnstein7.78(2)60(10)51(3) Hf IsotopeJL E(eV)   (meV)  n (meV) Present (196)37.432(197)20.903(198) Landolt-Börnstein72.5(3)4655(3) RESULTS: RESONANCES PARAMETERS OF Hf The 23rd March, Preparation For KPS Spring Meeting

Ta IsotopeJlE(eV)   (meV)  n (meV) Present (1)46.470(2)127.38(3) Landolt-Börnstein Present (31)43.889(32)7.4027(33) Landolt-Börnstein Present (4)42.969(5)3.2292(6) Landolt-Börnstein4.28(2)533.20(14) Present (34)34.66(35).58131(36) Landolt-Börnstein10.36(2)65(6)4.0(21) Present (7)140.69(8).18499(9) Landolt-Börnstein13.95(3)54(4)1.0133(3) Present (37)57.670(38)3.8820(39) Landolt-Börnstein20.29(3)52(4)1.0971(5) Present (40)203.25(41).64941(42) Landolt-Börnstein22.72(3)60(10)0.24(2) Present (10)63.168(11)2.1061(12) Landolt-Börnstein23.92(3)62(6)5.1555(2) Present (43)41.552(44).23283(45) Landolt-Börnstein30.02(3)55(11)0.32(3) Present (46)53.930(47) (48) Landolt-Börnstein34.19(3)60(10) (1) Present (49)196.01(50)55.065(51) Landolt-Börnstein35.14(3)69(7)18.286(10) RESULTS: RESONANCES PARAMETERS OF Ta The 23rd March, Preparation For KPS Spring Meeting

The present results are in good agreement with the evaluated data in ENDF/B-VI and the previous measurements. The resonance parameters of Hf and Ta isotopes have been determined by fitting the transmission data and their results are also in agreement with the previous ones. The SAMMY prediction of total cross-section and the present data are in good agreement with each other with  2/N=2.02. CONCLUSIONCONCLUSION The 23rd March, Preparation For KPS Spring Meeting