1. TOTAL CROSS-SECTION MEASUREMENTS AND RESONANCE PARAMETER ANNYLISIS OF 169 TM BELOW 100 EV ICTP, Trieste, Italy 2010/05/14 Presentation in the Workshop on Nuclear Data Wenming Wang

2. 2 This presentation is split into the following sections: 1Introduction 2Experimental Arrangements 3Data Processing and Analysis 4Conclusion Contents Presentation in ICTP 10/05/14

3. 3 The neutron resonance phenomenon is very common, which is of great importance in nuclear engineering and research. An Example of Neutron Resonance (Natural Tungsten, From EXFOR) 1Introduction Resolved region Unresolved region Presentation in ICTP 10/05/14

4. 4 The full flow of resonance parameter (RP) analysis usually contains the following three steps, that is data acquisition, data evaluation and data benchmark. Data Acquisition RP Generation and Evaluation Data Benchmark Testing 1Introduction white-light neutron source –Electron Linear Accelerator and bremsstrahlung –Spallation neutron source Using n-TOF method etc to get trans, cap, tot, fission… spectrum Using RP analysis tools(SAMMY, Atlas…) or codes to generate neutron RP According to the experimental environment, correct the exp data, including resolution and Doppler broadening, background correction etc. Using different series of data for evaluation Generate the formatted(ENDF) data sheet Comparing with the result of resonance integral experiment. Using the benchmark settings and MCNP code for simulation and testing If the result is not good enough, the flow should return to step II 1 2 3 Presentation in ICTP 10/05/14

5. 5 The commonly used tools for RP analysis are SAMMY, REFIT, etc., which are applied for nuclei with different weights and energy range. DetailsSketch Energy Unresolved EDA RUC SAMMY REFIT GNASH EMPIRE… EDA RUC SAMMY REFIT … Resolved LightHeavy Nuclei Weight EDA(LANL) and RUC(Prof. Chen.) are both R-matrix calculating codes, which can be used for light nuclei in full energy range. Gnash and Empire ( so do other codes such as UNF and Talys) are theoretical calculating codes for nuclear reaction, which can be use in fast region. SAMMY(ORNL) is a multi-level R-matrix fitting codes using bayesian equations, which is used for the analysis of 169 Tm data. 1Introduction Presentation in ICTP 10/05/14

6. 6 This presentation is split into the following sections: 1Introduction 2Experimental Arrangements 3Data Processing and Analysis 4Conclusion Contents Presentation in ICTP 10/05/14

7. 7 Time of flight method was widely applied in high-resolution trans measurement, which uses time signals corresponding to energy and trans ratio to get x-s. Principle of TOF methods L t0t0 t1t1 tntn NeutronDetector vivi 2Experimental Arrangements Presentation in ICTP 10/05/14

8. 8 The 169 Tm trans experiment was done in PNF, which was build in 1999, with four main components: Linac, target system, experimental hall, and data acquisition system. 2Experimental Arrangements Presentation in ICTP 10/05/14

9. 9 PNF can be used for neutron trans measurement, with an acceptable energy resolution below 100 eV, whose details can be seen elsewhere**. Pohang Neutron Facility (PNF)Key Components RF gun to produce electrons Electron Linear Accelerator (65 MeV) Water-cooled Ta-Target to produce white neutrons through bremsstrahlung –The calculated neutron yield can be above 10 12 n/kW.s Time of flight(TOF) experimental hall –TOF experimental Hall with a flight path of 12.06m –Automatic sample changer Data acquisition system –CAMAC and NIM module 2Experimental Arrangements **G N Kim, et al. J Kor. Phys. Soc. 43, 479 (2003) Presentation in ICTP 10/05/14

10. 10 Two Tm templates were used during this experiment, whose physical properties are as follows, as well as that of the notch filters. Tm Templates Notch Filter Templates 2Experimental Arrangements SamplePurity(%)Thickness(mm)Diameter(mm)Density(g/cm 3 ) 169 Tm99.95%1.41649.32 169 Tm99.95%0.41649.32 SamplePurity(%)Size(cm 2 )Thickness(mm)Density(g/cm 3 ) Cobalt99.910 * 100.58.90 Indium99.9910 * 100.27.31 Cadmium99.9910 * 100.58.65 Presentation in ICTP 10/05/14

11. 11 This presentation is split into the following sections: 1Introduction 2Experimental Arrangements 3Data Processing and Analysis 4Conclusion Contents Presentation in ICTP 10/05/14

12. 12 The energy calibration and background measurement were performed with notch filter methods, containing Co,Ta,In, Gd, with determined standard resonance below 100eV. The Background Spectrum 3Data Processing and Analysis Presentation in ICTP 10/05/14

13. 13 The energy calibration fitting is as follows, during which the dead time correction factor and flight path can be deduced. Energy Calibration Fitting Co,132eV In,9.04eV In,3.85eV In,1.457eV 3Data Processing and Analysis Presentation in ICTP 10/05/14

14. 14 After calibration and background measurements, two Tm templates were measured simultaneously, normalized with PICO record. 3Data Processing and Analysis Normalised Tm Data after De-background Experimental Details Exposure order: Thick  Thin  Open  Thick  …. Exposure Time: totally 80h, 5min for each position every cycle. Total counts: over 9k Normalization with PICO record, which has almost direct proportion with the incident neutron flux.: Re-shielding was carried out with olefin to eliminate the small defect at the edge of Tm templates. Presentation in ICTP 10/05/14

15. 15 After the background correction and normalization, we can get the transmission spectrum of Tm, which can be directly used for SAMMY analysis. 3Data Processing and Analysis Calculated Tm Trans Spectrum Details and Discussion The energy region with acceptable energy resolution is below 100 eV The sample templates is not thin enough, which leads to a black resonance at 3.9eV, increasing the uncertainty of fitting. Presentation in ICTP 10/05/14

16. 16 The total X-S spectrum can easily be deduced by trans spectrum, with a good agreement with the experimental data before**. 3Data Processing and Analysis Total X-S spectrum Details and Description The unusual data point has been eliminated before calculation The X-S has been averaged over energy The Mughabghab data are the re- construction curve from the recommended parameters from Mughabghab. **W M Wang, et al. CPC(HEP & NP), 34(2), 1-5 (2010) Presentation in ICTP 10/05/14

17. 17 The total uncertainty is consisted of two parts: the statistic uncertainty and systemic uncertainty. Uncertainty of X-S Uncertainty Analysis (simple) Factors on Energy Resolution Taking all factors into consideration, the total uncertainty of XS should be < 5% 3 169 Tm 共振能区中子全截面测量 Statistic error propagation ： Statistic uncertainty is around 4% Systemic uncertainty — from de-back (around 2% ） — from sample thickness measurement(around 2% ） —Others (less than1% ) Systemic uncertainty is less than 3% Through the relationship between flight time and energy, the energy resolution should be correlated to that of the flight path: Thus the factors on energy resolution should be as follows: Uncertainty from flight path fitting Uncertainty from dead(zero) time correction Others (like the position of detectors) Total energy resolution around 100 eV is 3.6%** ** G N Kim, et al. Nucl Instr and Meth A, 485 458-467 (2002) Presentation in ICTP 10/05/14

18. 18 Using SAMMY** code, the trans spectrum can be fitted property, with the Mughabghab parameters as start values and calculated correction factors as input. SAMMY Fitting Results 3Data Processing and Analysis ** N M Larson. Updated Users’ Guide for Sammy: Multilevel R-matrix Fits to Neutron Data Using Bayes’ Equations (2003) Presentation in ICTP 10/05/14

19. 19 The resonance parameters can be get through SAMMY fitting, whose results are of a little difference from that of Mughabghab. Parameters Comparison 3Data Processing and Analysis Discriptions The energy range is from 0.1 to 100 eV. This two series of parameters are a little bit different. Atlas is just the data recommended by Mughabghab. The parameters in red are of big uncertainties for black resonance or go far beyond the average capture width. The determination of capture width need more solid support of the capture measurements. E(eV)2gГn(meV)Гγ(meV) AtlasPresentAtlasPresentAtlasPresent -20.13-20.16 358 ± 4286.37173 ± 21 3.906 ± 0.001 （ 3.93 ） 11.2 ± 0.3 （ 17 ） 102.4 ± 1. 2 （ 131 ） 14.32 ± 0.0114.41 ± 0.034.56 ± 0.065.4 ± 0.597.1 ± 2.0160 ± 15 17.42 ± 0.0117.51 ± 0.022.87 ± 0.033.8 ± 0.581.4 ± 3.0107 ± 12 28.9 ± 0.1 0.31 ± 0.030.42 ± 0.0495 ± 2093 ± 20 34.79 ± 0.0534.86 ± 0.068.8 ± 0.514.1 ± 1.086 ± 3113 ± 20 37.51 ± 0.0537.47 ± 0.050.69 ± 0.070.8 ± 0.1 （ 5.0 ） 44.79 ± 0.0544.87 ± 0.065.2 ± 0.37.0 ± 1.093 ± 597 ± 8 50.58 ± 0.1050.7 ± 0.38.1 ± 0.812.0 ± 2.079 ± 574 ± 5 59.07 ± 0.1058.5 ± 0.315.0 ± 0.925 ± 3.084 ± 566 ± 6 62.97 ± 0.1062.9 ± 0.21.5 ± 0.21.2 ± 0.578 ± 1576 ± 15 65.75 ± 0.1065.90 ± 0.256.5 ± 1.571 ± 583 ± 497 ± 15 83.18 ± 0.1083.53 ± 0.311.3 ± 0.615 ± 185 ± 583 ± 10 94.1 ± 0.194.6 ± 0.348 ± 558 ± 8 （ 4.9 ） 95.4 ± 0.195.6 ± 0.31.9 ± 0.23.5 ± 1.071 ± 2071 ± 15 Presentation in ICTP 10/05/14

20. 20 This presentation is split into the following sections: 1Introduction 2Experimental Arrangements 3Data Processing and Analysis 4Conclusion Contents Presentation in ICTP 10/05/14

21. 21 Taking all experimental data available into consideration, the RP of 169 Tm below 100 eV may be determined as follows. ( still under discussion) Recommended RP 3Conclusion and Discussion Basis of Recommendation J parameters are from the polarization measurement of Alfimenkov in JNR in 1982 E and Г parameters are determined mainly on 4 series of data including present one —Mughabghab’s parameters —1973, Tellies, et al, on SACLAY —1999, Danon, et al, on RPI —Present one, on PNF Гγ from Mughabghab RP at 3.9eV from Danon Others from present results JE(eV)2gГn(meV)Гγ(meV) 1-20.1335886.37 13.906±0.00111.2±0.3102.4±1.2 014.36±0.044.9±0.397.1±2.0 017.47±0.053.34±0.481.4±3.0 128.9±0.10.42±0.0495±20 134.86±0.0614.1±1.086±3 137.47±0.050.8±0.1 144.87±0.067.0±1.093±5 150.7±0.312.0±2.079±5 158.5±0.325±3.084±5 162.9±0.21.2±0.578±15 065.90±0.2071±583±4 183.53±0.3015±185±5 194.6±0.358±8 095.6±0.33.5±1.071±20 Presentation in ICTP 10/05/14