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Title: 120 GeV neutrino physics graphite target damage assessment using electron microscopy and high-energy x-ray diffraction at NSLS II Synchrotron

Abstract

The NT-02 neutrino physics target made of the isotropic graphite grade produced neutrinos for the MINOS and MINERVA high energy physics experiments. The segmented, 95 cm long NT-02 target was bombarded with a 340 kW, Gaussian 1.1 mm sigma beam of 120 GeV protons reaching 6.516x10 20 protons on target (POT) and a peak fluence of 8.6x10 21 protons/cm 2. Reduction in detected neutrino events during the experiment were attributed to radiation-induced damage on the target material leading to the NT-02 target replacement. With future neutrino physics targets aiming at multi-MW power regime identifying life expectancy or fluence thresholds of target materials are of paramount importance and therefore pinpointing the exact cause and target failure mode triggering the neutrino yield reduction is critical. To help unravel the effects of the 120 GeV beam on the isotropic graphite structure at the microstructural/lattice level X-ray beams from NSLS II were utilized to study failed in-beam as well as intact NT-02 target segments. The primary objective was to arrive at a scientifically sound explanation of the processes responsible for the target failure by correlating macroscopic observations with microstructural analyses. Results from transmission electron microscopy studies were integrated in the assessing microstructural evolution. Themore » X-ray diffraction study revealed (a) the diffused state reached by the graphite microstructure within the 1σ of the beam where the graphite lattice structure transforming into nanocrystalline structure, a finding supported by electron microscopy examination, thus providing an indication of fluence threshold and (b) the dominant role of the irradiation temperature profile exhibiting high gradient from the beam center to the heat sink and aggravating the damage induced in the microstructure by the high proton fluence. The effects of the 120 GeV protons on the isotropic graphite target structure are corroborated by observed damage induced by 160 MeV protons and by fast neutrons to comparative doses on similar graphite, an assessment that will aid the design of next generation MWclass neutrino targets.« less

Authors:
 [1];  [2];  [3];  [4];  [3];  [4];  [3];  [5];  [2];  [2];  [2];  [2];  [2];  [6];  [6]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States)
  2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
  4. Stony Brook Univ., NY (United States)
  5. National Center for Scientific Research “Demokritos”, Athens (Greece)
  6. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
1505665
Alternate Identifier(s):
OSTI ID: 1503517; OSTI ID: 1508021
Report Number(s):
BNL-211461-2019-JAAM; FERMILAB-PUB-19-155-AD
Journal ID: ISSN 2469-9888; PRABCJ
Grant/Contract Number:  
SC0012704; AC02-07CH11359; CT-13BN040505; SC-0012704
Resource Type:
Published Article
Journal Name:
Physical Review Accelerators and Beams
Additional Journal Information:
Journal Volume: 22; Journal Issue: 4; Journal ID: ISSN 2469-9888
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; Neutrino physics; isotropic graphite; irradiation damage; annealing; x-ray diffraction

Citation Formats

Simos, Nikolaos, Hurh, P., Dooryhee, E., Snead, L., Zhong, Z., Zhong, H., Ghose, S., Kotsina, Z., Kotsina, Z., Ammigan, K., Hylen, J., Papadimitriou, V., Zwaska, R., Senor, D., and Casella, A. 120 GeV neutrino physics graphite target damage assessment using electron microscopy and high-energy x-ray diffraction at NSLS II Synchrotron. United States: N. p., 2019. Web. doi:10.1103/PhysRevAccelBeams.22.041001.
Simos, Nikolaos, Hurh, P., Dooryhee, E., Snead, L., Zhong, Z., Zhong, H., Ghose, S., Kotsina, Z., Kotsina, Z., Ammigan, K., Hylen, J., Papadimitriou, V., Zwaska, R., Senor, D., & Casella, A. 120 GeV neutrino physics graphite target damage assessment using electron microscopy and high-energy x-ray diffraction at NSLS II Synchrotron. United States. doi:10.1103/PhysRevAccelBeams.22.041001.
Simos, Nikolaos, Hurh, P., Dooryhee, E., Snead, L., Zhong, Z., Zhong, H., Ghose, S., Kotsina, Z., Kotsina, Z., Ammigan, K., Hylen, J., Papadimitriou, V., Zwaska, R., Senor, D., and Casella, A. Mon . "120 GeV neutrino physics graphite target damage assessment using electron microscopy and high-energy x-ray diffraction at NSLS II Synchrotron". United States. doi:10.1103/PhysRevAccelBeams.22.041001.
@article{osti_1505665,
title = {120 GeV neutrino physics graphite target damage assessment using electron microscopy and high-energy x-ray diffraction at NSLS II Synchrotron},
author = {Simos, Nikolaos and Hurh, P. and Dooryhee, E. and Snead, L. and Zhong, Z. and Zhong, H. and Ghose, S. and Kotsina, Z. and Kotsina, Z. and Ammigan, K. and Hylen, J. and Papadimitriou, V. and Zwaska, R. and Senor, D. and Casella, A.},
abstractNote = {The NT-02 neutrino physics target made of the isotropic graphite grade produced neutrinos for the MINOS and MINERVA high energy physics experiments. The segmented, 95 cm long NT-02 target was bombarded with a 340 kW, Gaussian 1.1 mm sigma beam of 120 GeV protons reaching 6.516x1020 protons on target (POT) and a peak fluence of 8.6x1021 protons/cm2. Reduction in detected neutrino events during the experiment were attributed to radiation-induced damage on the target material leading to the NT-02 target replacement. With future neutrino physics targets aiming at multi-MW power regime identifying life expectancy or fluence thresholds of target materials are of paramount importance and therefore pinpointing the exact cause and target failure mode triggering the neutrino yield reduction is critical. To help unravel the effects of the 120 GeV beam on the isotropic graphite structure at the microstructural/lattice level X-ray beams from NSLS II were utilized to study failed in-beam as well as intact NT-02 target segments. The primary objective was to arrive at a scientifically sound explanation of the processes responsible for the target failure by correlating macroscopic observations with microstructural analyses. Results from transmission electron microscopy studies were integrated in the assessing microstructural evolution. The X-ray diffraction study revealed (a) the diffused state reached by the graphite microstructure within the 1σ of the beam where the graphite lattice structure transforming into nanocrystalline structure, a finding supported by electron microscopy examination, thus providing an indication of fluence threshold and (b) the dominant role of the irradiation temperature profile exhibiting high gradient from the beam center to the heat sink and aggravating the damage induced in the microstructure by the high proton fluence. The effects of the 120 GeV protons on the isotropic graphite target structure are corroborated by observed damage induced by 160 MeV protons and by fast neutrons to comparative doses on similar graphite, an assessment that will aid the design of next generation MWclass neutrino targets.},
doi = {10.1103/PhysRevAccelBeams.22.041001},
journal = {Physical Review Accelerators and Beams},
number = 4,
volume = 22,
place = {United States},
year = {2019},
month = {4}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1103/PhysRevAccelBeams.22.041001

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