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TOTAL CROSS-SECTION MEASUREMENTS AND RESONANCE PARAMETER ANNYLISIS OF 169 TM BELOW 100 EV

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. Contents. This presentation is split into the following sections:. 1 Introduction.

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TOTAL CROSS-SECTION MEASUREMENTS AND RESONANCE PARAMETER ANNYLISIS OF 169 TM BELOW 100 EV

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

  2. Contents This presentation is split into the following sections: Presentation in ICTP10/05/14

  3. 1 Introduction 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) Unresolved region Resolved region Presentation in ICTP10/05/14

  4. 1 Introduction The full flow of resonance parameter (RP) analysis usually contains the following three steps, that is data acquisition, data evaluation and data benchmark. 1 Data Acquisition • 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 2 RP Generation and Evaluation 3 • 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 Data Benchmark Testing Presentation in ICTP10/05/14

  5. 1 Introduction The commonly used tools for RP analysis are SAMMY, REFIT, etc. , which are applied for nuclei with different weights and energy range. Details Sketch • 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 169Tm data. Presentation in ICTP10/05/14

  6. Contents This presentation is split into the following sections: Presentation in ICTP10/05/14

  7. t0 tn t1 Neutron Detector L 2 Experimental Arrangements 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 vi Presentation in ICTP10/05/14

  8. Detector Target room BC702 EG&G Ortec Part AMP HV PSA Delay TAC Iron Turbo-MCS H3BO3 Pb SCA TSCA START STOP Gate & Sample TTL/NIM Delay Changer Generator Sample changer 12.06 m Water moderator CAMAC Part Decimal Detector 5.4 m Counter Number Concrete 1.8 m Encoder BMPI TTL/NIM STOP Time SC Encoder START 2.9 m Gate & Contrl Delay Sample Changer Generator LINAC MEM116k 100 MeV LINAC Ta -target RF Ta target Trigger 2 Experimental Arrangements The 169Tm trans experiment was done in PNF, which was build in 1999, with four main components: Linac, target system, experimental hall, and data acquisition system. Presentation in ICTP10/05/14

  9. 2 Experimental Arrangements 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 1012 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 **G N Kim, et al. J Kor. Phys. Soc. 43, 479 (2003) Presentation in ICTP10/05/14

  10. 2 Experimental Arrangements 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 Presentation in ICTP10/05/14

  11. Contents This presentation is split into the following sections: Presentation in ICTP10/05/14

  12. 3 Data Processing and Analysis 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 Presentation in ICTP10/05/14

  13. 3 Data Processing and Analysis The energy calibration fitting is as follows, during which the dead time correction factor and flight path can be deduced. Energy Calibration Fitting In,1.457eV In,3.85eV In,9.04eV Co,132eV Presentation in ICTP10/05/14

  14. 3 Data Processing and Analysis After calibration and background measurements, two Tm templates were measured simultaneously, normalized with PICO record. Normalised Tm Data after De-background • 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. Experimental Details Presentation in ICTP10/05/14

  15. 3 Data Processing and Analysis After the background correction and normalization, we can get the transmission spectrum of Tm, which can be directly used for SAMMY analysis. Calculated Tm Trans Spectrum • 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. Details and Discussion Presentation in ICTP10/05/14

  16. 3 Data Processing and Analysis The total X-S spectrum can easily be deduced by trans spectrum, with a good agreement with the experimental data before**. Total X-S spectrum • 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. Details and Description **W M Wang, et al. CPC(HEP & NP), 34(2), 1-5 (2010) Presentation in ICTP10/05/14

  17. 3 169Tm共振能区中子全截面测量 The total uncertainty is consisted of two parts: the statistic uncertainty and systemic uncertainty. Uncertainty Analysis (simple) Uncertainty of X-S Factors on Energy Resolution • 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%** Taking all factors into consideration, the total uncertainty of XS should be < 5% ** G N Kim, et al. Nucl Instr and Meth A, 485 458-467 (2002) Presentation in ICTP10/05/14

  18. 3 Data Processing and Analysis 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 ** N M Larson. Updated Users’ Guide for Sammy: Multilevel R-matrix Fits to Neutron Data Using Bayes’ Equations (2003) Presentation in ICTP10/05/14

  19. 3 Data Processing and Analysis The resonance parameters can be get through SAMMY fitting, whose results are of a little difference from that of Mughabghab. Parameters Comparison Discriptions • The energy range is from 0.1 to 100 eV. • This two series of parameters are a little bit different. • Atlasis 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. Presentation in ICTP10/05/14

  20. Contents This presentation is split into the following sections: Presentation in ICTP10/05/14

  21. 3 Conclusion and Discussion Taking all experimental data available into consideration, the RP of 169Tm below 100 eV may be determined as follows. ( still under discussion) Recommended RP Basis of Recommendation • J parameters are from the polarization measurement of Alfimenkov in JNR in 1982 • E and Гparameters 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 Presentation in ICTP10/05/14

  22. Thanks For Ur Attention

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