1. Name of Experiment:
 ------------------
 Karlsruhe Iron Sphere Benchmark Experiment (1975)


2. Purpose and Phenomena Tested:
 ----------------------------
 Determination of neutron leakage spectra from a set of iron spheres of diameters 15,
 20, 25, 30, 35, and 40 cm, with a Cf-252 neutron source in the centre.

 The aim of this experiment was to check especially the iron inelastic scattering
 cross-sections. Pure iron and a spherical geometry were used to facilitate the
 interpretation of results.

3. Description of the Source and Experimental Configuration:
 --------------------------------------------------------
 The neutron source consisted of about 30 micrograms Cf-252, corresponding to a
 source strength of about 7E7 n/sec. Cf-252 source was contained in a double-walled
 capsule and inserted to the centre of an iron sphere through a cylindrical channel,
 which thereafter was filled up. Six iron spheres having different diameters were
 investigated. High purity iron (C 0.07%, Mn 0.05%, P 0.009%, S 0.007%) was used. The
 arrangement was located in a hall with a minimal distance of 2 m to the ground and
 more than 3 m to the next wall in order to reduce the background due to scattered
 neutrons.

4. Measurement System and Uncertainties:
 ------------------------------------
 The detectors used were:

 Detector Diameter Effective Statistical System
 (mm) Length (mm) Error (%) Error (%)
 ---------------------------------------------------------------------
 proton recoil spec. 4.8 12.6 5 - 10 8 - 11
 proton recoil spec. 8.9 83.5 5 - 10 8 - 11
 He-3 spec. 5 - 10 5 - 6
 ---------------------------------------------------------------------

5. Description of Results and Analysis:
 -----------------------------------

 Using cylindrical gas-filled proton-recoil proportional counters the integral (angle
 integrated) neutron leakage spectra and by means of collimators also angular
 dependent neutron spectra in the energy region from 60 keV to 5 MeV were measured.
 The spectra were measured at a distance of about 1 m from the sphere centre with the
 axis in the radial direction. The room-scattered background was corrected for by
 evaluation of the difference of spectra from measurements without and with a shadow
 cone.

 The integral leakage spectra, measured with the proton-recoil proportional counters,
 were normalized to one source neutron. The spectra were unfolded with the SPEC-4
 code [6].

 Using small He-3 semiconductor spectrometers, which were located directly on the
 surface of the sphere, scalar neutron spectra were measured in the energy region
 from 100 keV to 8 MeV. Measurements were corrected for the background due to (n,d)
 and (n,p) events and unfolded through the program described in [7]. The spectra are
 given in relative values only.

 In addition to the iron spectra the pure Cf-252 source spectrum was measured.

 A 1-D calculational model has been recommended by the authors. Some calculations are
 described in ref. [1], [2], [3], [4].

6. Special Features:
 ----------------

 None

7. Author/Organizer
 ----------------
 Experiment and analysis:
 H. Werle, H. Bluhm, G. Fieg, F. Kappler, D. Kuhn, and M. Lalovic
 Forschungszentrum Karlsruhe, P.O. box 3640, D-76021 Karlsruhe, Germany

 Compiler of data for SINBAD:
 I. Kodeli
 OECD/NEA, 12 bd des Iles, 92130 Issy les Moulineaux, France
 E-mail: ivan.kodeli@ijs.si

 Reviewer of compiled data:
 H. Werle
 Forschungszentrum Karlsruhe, P.O. box 3640, D-76021 Karlsruhe, Germany

8. Availability:
 ------------

 Unrestricted

9. References:
 ----------

 [1] H. Werle, H. Bluhm, G. Fieg, F. Kappler, D. Kuhn, and M. Lalovic, "Neutron
 Leakage Spectra from Iron Spheres with a Cf-252 Neutron Source in the Centre",
 Proceedings of the Specialists' Meeting on Sensitivity Studies and Shielding
 Benchmarks, Paris (Oct. 1975)
 [2] H. Werle et al., Report KFK 2219 (1975); English translation in EURFNR - 1317
 (1975)
 [3] M. Lanfranchi, J. F. Jaeger, "Shielding Benchmarks. Some Considerations on Three
 Iron Shielding Benchmarks", EIR Report, TM-45-86-33, NEACRP Specialists' Meeting
 on Shielding Benchmarks, Paris (Oct. 1986)
 [4] J. Hasnip, V. Herrnberger, "Analysis of Fe-Shielding Benchmark Experiments by
 the JEF-1/EFF-Library", NEACRP Specialists' Meeting on Shielding Benchmarks,
 Paris (Oct. 1986)
 [5] H. Werle, Nucl. Instr. Meth. 99 (1972) 295
 [6] P. W. Benjamin et al., "The analysis of recoil proton spectra", Report AWRE
 No. 09/68 (1968)
 [7] H. Bluhm, Nucl. Instr. Meth. 115 (1974) 325
 [8] R. Nicks, "Results of the First Four Single-Material Experiments in Iron",
 NEACRP-U-73 (1976)

10. Data and Format:
 ---------------

 DETAILED FILE DESCRIPTIONS
 --------------------------
 Filename Size[bytes] Content
 ---------------- ----------- -------------
 1 kfk-abs.htm 8.554 This information file
 2 kfk-exp.htm 27.582 Description of Experiment
 3 KFK-F1.TIF 239.613 Figure 1: Photo of the measurement facility (high quality)
 4 KFK-F2.TIF 56.898 Figure 2: Neutron source geometry (high quality)
 5 KFK-F3.TIF 33.777 Figure 3: Lay out of the leakage spectra measurements 
   (high quality)
 6 KFK-F4.TIF 33.866 Figure 4: Lay out of the angular flux measurements 
   (high quality)
 7 KFK-F5.TIF 61.223 Figure 5: Angular flux measured by proton recoil 
   detectors (FE40) (high quality)
 8 Kfk-f1.gif 183.212 Figure 1: Photo of the measurement facility (preview)
 9 Kfk-f2.gif 17.231 Figure 2: Neutron source geometry (preview)
10 Kfk-f3.gif 5.033 Figure 3: Lay out of the leakage spectra measurements
   (preview)
11 Kfk-f4.gif 5.542 Figure 4: Lay out of the angular flux measurements (preview)
12 Kfk-f5.gif 7.263 Figure 5: Angular flux measured by proton recoil detectors
   (FE40) (preview)
13 KFK_1.pdf 177.580 Reference
14 KFK_2A.pdf 2.349.486 Reference
15 KFK_2D.pdf 2.034.147 Reference
16 KFK_5.pdf 465.886 Reference
17 KFK_8.pdf 2.574.681 Reference
18 J1330.pdf 3.824.302 Reference


 Figures are stored in TIFF format using LZW compression and GIF format (preview).

 File kfk-exp.HTM contains the following tables:
 (1) Normalized source spectrum,
 (2, 3) Proton recoil detector characteristics and geometry,
 (4, 5) Measurement errors,
 (6, 7) Measured results.