COHERENT Collaboration data release from the first detection of coherent elastic neutrino-nucleus scattering on argon
COHERENT Collaboration, D. Akimov, J.B. Albert, P. An, C. Awe, P.S. Barbeau, B. Becker, V. Belov, M.A. Blackston, L. Blokland, A. Bolozdynya, B. Cabrera-Palmer, N. Chen, D. Chernyak, E. Conley, R.L. Cooper, J. Daughhetee, M. del Valle Coello, J.A. Detwiler, M.R. Durand, Y. Efremenko, S.R. Elliott, L. Fabris, M. Febbraro, W. Fox, A. Galindo-Uribarri, M.P. Green, K.S. Hansen, M.R. Heath, S. Hedges, M. Hughes, T. Johnson, M. Kaemingk, L.J. Kaufman, A. Khromov, A. Konovalov, E. Kozlova, A. Kumpan, L. Li, J.T. Librande, J.M. Link, J. Liu, K. Mann, D.M. Markoff, O. McGoldrick, H. Moreno, P.E. Mueller, J. Newby, D.S. Parno, S. Penttila, D. Pershey, D. Radford, R. Rapp, H. Ray, J. Raybern, O. Razuvaeva, D. Reyna, G.C. Rich, D. Rudik, J. Runge, D.J. Salvat, K. Scholberg, A. Shakirov, G. Simakov, G. Sinev, W.M. Snow, V. Sosnovtsev, B. Suh, R. Tayloe, K. Tellez-Giron-Flores, R.T. Thornton, I. Tolstukhin, J. Vanderwerp, R.L. Varner, C.J. Virtue, G. Visser, C. Wiseman, T. Wongjirad, J. Yang, Y.-R. Yen, J. Yoo, C.-H. Yu, J. Zettlemoyer
CCOHERENT Collaboration data release from the first detection of coherentelastic neutrino-nucleus scattering on argon
D. Akimov a,b , J.B. Albert c , P. An d,e , C. Awe d,e , P.S. Barbeau d,e , B. Becker f , V. Belov a,b , M.A. Blackston g ,L. Blokland f , A. Bolozdynya b , B. Cabrera-Palmer h , N. Chen i , D. Chernyak j , E. Conley d , R.L. Cooper k,l ,J. Daughhetee f , M. del Valle Coello c , J.A. Detwiler i , M.R. Durand i , Y. Efremenko f,g , S.R. Elliott l ,L. Fabris g , M. Febbraro g , W. Fox c , A. Galindo-Uribarri f,g , M.P. Green e,g,m , K.S. Hansen i , M.R. Heath g ,S. Hedges d,e , M. Hughes c , T. Johnson d,e , M. Kaemingk k , L.J. Kaufman c,1 , A. Khromov b , A. Konovalov a,b ,E. Kozlova a,b , A. Kumpan b , L. Li d,e , J.T. Librande i , J.M. Link n , J. Liu j , K. Mann e,m , D.M. Markoff e,o ,O. McGoldrick i , H. Moreno k , P.E. Mueller g , J. Newby g , D.S. Parno p , S. Penttila g , D. Pershey d ,D. Radford g , R. Rapp p , H. Ray q , J. Raybern d , O. Razuvaeva a,b , D. Reyna h , G.C. Rich r,s , D. Rudik a,b ,J. Runge d,e , D.J. Salvat c , K. Scholberg d , A. Shakirov b , G. Simakov a,b,t , G. Sinev d , W.M. Snow c ,V. Sosnovtsev b , B. Suh c , R. Tayloe c , K. Tellez-Giron-Flores n , R.T. Thornton c,l , I. Tolstukhin c,2 ,J. Vanderwerp c , R.L. Varner g , C.J. Virtue u , G. Visser c , C. Wiseman i , T. Wongjirad v , J. Yang v ,Y.-R. Yen p , J. Yoo w,x , C.-H. Yu g , J. Zettlemoyer c a Institute for Theoretical and Experimental Physics named by A.I. Alikhanov of National Research Centre “KurchatovInstitute”, Moscow, 117218, Russian Federation b National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow, 115409, Russian Federation c Department of Physics, Indiana University, Bloomington, IN, 47405, USA d Department of Physics, Duke University, Durham, NC 27708, USA e Triangle Universities Nuclear Laboratory, Durham, North Carolina, 27708, USA f Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA g Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA h Sandia National Laboratories, Livermore, CA 94550, USA i Department of Physics and Center for Experimental Nuclear Physics and Astrophysics,University of Washington, Seattle, WA 98195, USA j Physics Department, University of South Dakota, Vermillion, SD 57069, USA k Department of Physics, New Mexico State University, Las Cruces, NM 88003, USA l Los Alamos National Laboratory, Los Alamos, NM, USA, 87545, USA m Physics Department, North Carolina State University, Raleigh, NC 27695, USA n Center for Neutrino Physics, Virginia Tech, Blacksburg, VA 24061, USA o Department of Mathematics and Physics, North Carolina Central University, Durham, NC, 27707, USA p Carnegie Mellon University, Pittsburgh, PA 15213, USA q Department of Physics, University of Florida, Gainesville, FL 32611, USA r Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA s Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA t Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russian Federation u Department of Physics, Laurentian University, Sudbury, Ontario P3E 2C6, Canada v Department of Physics and Astronomy, Tufts University, Medford, MA 02155, USA w Department of Physics at Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea x Center for Axion and Precision Physics Research (CAPP) at Institute for Basic Science (IBS), Daejeon, 34141, Republic ofKorea
The enclosed data release includes the information to analyze the COHERENT data published in Ref. [1].The data, the CEvNS signal, and the associated backgrounds are shared in a binned text file format alongwith associated uncertainties. The binning of the data in the text file is identical to that in Ref. [1]. Thisdocument provides information on the enclosed data release and guidance on the use of the data. Presently at SLAC National Accelerator Laboratory, Menlo Park, CA 94205, USA Presently at Argonne National Laboratory, Argonne, IL 60439, USA a r X i v : . [ nu c l - e x ] J u l imension Unit Range Bin Width Total BinsEnergy keVee 0 – 120 10 12 F F t trig µ s -0.1 – 4.9 0.5 10 Table 1
1. Overview of the release
This data release follows “Analysis A” of Ref. [1] with the information included within the release andin this document. As “Analysis B” gives consistent results as reported in Ref. [1], it is not reported aspart of this release. The data release, this accompanying document, and code examples provided withthe release are available in two locations: at http://coherent.ornl.gov/data and also on Zenodo (DOI: ). See Sec. 5 for comments on how to use the released data. See Sec. 6 for how tocite this data. Please direct questions about the material provided within this release to [email protected] (J. Zettlemoyer) and/or [email protected] (R. Tayloe).
There are two main methods of distributing the relevant information in this data release. The provideddata and signal/background probability distribution functions (PDFs) are included as 3D binned arrays intext file formats. They are identically binned in the 3D space in energy, F , and time to trigger ( t trig ) asin Ref. [1]. The binning is given in Table 1. Values such as the neutrino flux with associated uncertaintiesare provided in a YAML file format as in the previous collaboration data release [2] accompanying the firstobservation of CEvNS in Ref. [3]. The YAML format and the parameter values included are described inSec. 2.8. All files described here are located in the Data directory of this release.For analyses that do not require the entire 3-dimensional information, 1-dimensional projections in theform of binned text files that include all the information to recreate Fig. 4 of Ref. [1] are also includedas part of this data release with the format of the lines described at the top of the file. These files arelocated in the
Data/OneDProjections directory of the release and are labeled energydata1d.txt for en-ergy, f90data1d.txt for F , and timingdata1d.txt for t trig .
2. Included within release
A description of the major contents of the release is below.
For the SNS data, both “on-beam” (SNS beam data, datanobkgsub.txt ) and “off-beam” (measuredsteady-state backgrounds, bkgpdf.txt ) triggered data are included separately. Both are provided as a tab-separated-value text file with in the form of: bin center in energy[keVee], bin center in F [ F ], bin centerin t trig [ µ s ], number of events/bin/6.12 GWhr. The number of total bins and bin widths in each dimensionis the same as for Analysis A in Ref. [1] and described in Tab. 1. The CEvNS signal PDF used in Analysis A of Ref. [1] is included as part of this data release. The providedtext file ( cevnspdf.txt ) is normalized to the initial central value (CV) SM prediction from Analysis A ofthe COHERENT data. This information is provided in the same way as the SNS data. The normalizationsfor both the best-fit result and the SM prediction are included in the YAML file describing single-valueparameters. The CEvNS signal was allowed to float during the likelihood fit in the analysis of Ref. [1] butan uncertainty is included representing the cross-section systematic errors as in Tab. 2 of Ref. [1].This release also includes information on the measured energy resolution and the SNS timing parameters.The SNS protons-on-target trace is well-approximated by a Gaussian distribution. The YAML file includes2istribution File CV Prediction Best-fit resultOn-beam Data datanobkgsub.txt cevnspdf.txt ±
17 159 ± brnpdf.txt ±
160 553 ± delbrnpdf.txt ±
33 10 ± bkgpdf.txt ±
25 3131 ± Table 2: Summary of information provided in the text files the mean and width of the distribution and the uncertainties on those values with respect to t trig . The F distribution can be examined by looking at the 2-D projection in F and energy within the binned PDF cevnspdf.txt . The prompt BRN PDF from Analysis A of Ref. [1] is included within the release. As they are treated asseparate components during the likelihood analysis in Ref. [1], the delayed BRN PDF is included separately.As for the CEvNS PDF, the prompt and delayed BRN PDFs is normalized within the text files ( brnpdf.txt for prompt BRN, delbrnpdf.txt for delayed BRN) to the initial central value (CV) prediction from Anal-ysis A. An uncertainty value located in the YAML file represents the width of a Gaussian constraint Thenormalization for the best-fit result is also included within the YAML file and can be renormalized if needed.
The steady-state background ( bkgpdf.txt ) PDF is the measured off-beam data. The separate off-beamtrigger computes the steady-state contribution in situ . The energy and F components of the PDF comedirectly from the measured off-beam data. The time component is included as a constant over the consideredtime range. The steady-state PDF is normalized within the text file ( bkgpdf.txt ) to the CV predictionfrom Analysis A. An uncertainty value which represents the width of a Gaussian constraint is included inthe YAML file. The normalization for the best-fit result is also included within the YAML file and can berenormalized if needed.Note that the steady-state background is originally oversampled from a 5x larger window with respectto t trig than the data to reduce the statistical error on the background. This has been taken into accountin the provided PDF and the normalization includes this information. However, when a subtraction of thesteady-state background is performed on the data within an analysis, the consequence of the oversamplingmust be applied. To do so, the error on each bin is not √ N , but √ N . A summary of the information described in this section is given in Tab. 2.
The detector efficiency after cuts is included as a separate text file (
CENNS10AnlAEfficiency.txt ) inenergy space with lines: bin center in keVee, bin center in keVnr, efficiency. This includes effects of cuts in F space corresponding to those used in Analysis A of Ref. [1]. Use a flat efficiency value corresponding tothe value in the last bin for any reconstructed energies larger than those given in the text file. The energy resolution is well described by σ E E = a √ E ( keV ee ) and included as part of the data release insidethe YAML file. The value of the parameter a is determined from the m Kr calibration data and confirmedusing the CENNS-10 simulation. 3 .8. Single-Value/Functional Parameters
A YAML file (
LArParametersAnlA.yaml ) represents parameters represented with a single-value or afunctional form included within this release. An entry in the YAML file includes the parameter of functionvalues, uncertainties, and a comment describing the parameter of function. In the case of a function thefunctional form is provided in the comment. The parameters included in the YAML file are: • Beam exposure • Distance to SNS target • Detector mass • Quenching Factor (QF) • ν /proton • Best-fit normalizations with uncertainties for CEvNS, prompt and delayed BRN, and steady-statebackground • Initial CV prediction normalizations with prior uncertainties for CEvNS, prompt and delayed BRN,and steady-state background • Detector efficiency • Energy Resolution • SNS protons-on-target timingAn example entry is here: beamExposure : name : Beam e x p o s u r e v a l u e : 1 3 . 8 u n i t s : E22 POT u n c e r t a i n t y : n e g l i g i b l e comment : | SNS beam e x p o s u r e f o r t h e f i r s t CEvNS d e t e c t i o n on l i q u i d a r g o ni n terms o f p r o t o n s on t a r g e t . I t r e p r e s e n t s 6 . 1 2 GWhr o fi n t e g r a t e d beam power .
An example entry for a parameter described by a function is here: larQF : name : LAr q u e n c h i n g f a c t o r p a r a m e t e r s :- name : a v a l u e : 0 . 2 4 6 u n c e r t a i n t y : 0 . 0 0 6- name : b v a l u e : 0 . 0 0 0 7 8 u n c e r t a i n t y : 0 . 0 0 0 0 9 comment : | Form o f QF = a + bT ( keVnr ) where T i s t h e r e c o i l e n e r g y i n u n i t so f keVnr . T h i s v a l u e f o r t h e QF was d e t e r m i n e d b a s e d on a l i n e a rf i t t o a l l a v a i l a b l e d a t a p o i n t s from t h e l i t e r a t u r e i n t h er a n g e 0 −
125 keVnr . F u r t h e r d e s c r i b e d i n \ p r o t e c t \ v r u l e w i d t h 0 p t \ p r o t e c t \ h r e f { h t t p : / / a r x i v . o r g / a b s / 2 0 0 3 . 1 0 6 3 0 } { a r X i v : 2 0 0 3 . 1 0 6 3 0 } .4ystematic CEvNS Prompt BRNCEvNS F E dependence cevnspdf-1sigF90.txt brnpdf.txtcevnspdf+1sigF90.txt
CEvNS t trig mean cevnspdfCEvNSTimingMeanSyst.txt brnpdf.txt BRN E dist. cevnspdf.txt brnpdf-1sigEnergy.txtbrnpdf+1sigEnergy.txt
BRN t trig mean cevnspdf.txt brnpdf-1sigBRNTimingMean.txtbrnpdf+1sigBRNTimingMean.txt BRN t trig width cevnspdf.txt brnpdfBRNTimingWidthSyst.txt Table 3: Details of systematic PDFs corresponding to the error bands in Fig. 4 of Ref. [1]. For an analysis, the rows of thetable correspond to which PDFs to fit to the data to replicate a certain systematic effect.
3. Systematic Errors
The systematic error PDFs corresponding to the systematic error bands from Analysis A shown in Fig. 4of Ref. [1] are also a part of this release. These PDFs represent the various fit systematics obtained in Tab.1 of Ref. [1]. The PDFs representing the systematic errors are found in the
Data/SystErrors directory ofthe release. They are provided if the need arises to apply these systematics to models within a separateanalysis using the data. The data are fit with alternative PDFs to generate the systematic error envelope.Each bin of a 1-D projection contains a systematic error that is the envelope of the alternative fit results.The systematic PDFs are included in the same binned text file format as the central value PDFs. The setof files used to compute each systematic is given in Tab. 3, with both a ± σ systematic PDF given whereapplicable. The difference between the ± σ PDFs are provided in the filenames with a ’-’ in the filenamerepresenting − σ and a ’+’ in the filename representing +1 σ for a given systematic. The labels given tothe systematics is the same as in Tab. 1 of Ref. [1]. Note that every entry in Tab. 3 requires thesteady-state background file bkgpdf.txt and the delayed BRN file delbrnpdf.txt within a fitusing the systematic error PDFs but is not explicitly written in Tab. 3 .For those not interested in performing separate systematic fits to the provided data as part of an anal-ysis, the systematic errors are also included in a 1-dimensional binned tab-separated text file. The lines ofthese files are formatted as: bin center[units], syst. error min as fraction of bin value, syst. error max asfraction of bin value. For the three dimensions, the corresponding files with the appropriate units are: en-ergy[keVee]( systerrors1denergy.txt ), F [ F ]( systerrors1dpsd.txt ), t trig [ µ s]( systerrors1dtime.txt ).
4. Example Code
PlotExtractedData.C is an example ROOT-based macro which parses the text files provided in thisrelease and remakes Fig. 4 of Ref. [1]. The code is located in the
ExampleCode directory of the release. Thecode gives an example of how to extract the data, compute statistical and systematic errors, and comparethe PDFs to the data. The resulting projections generated by this example script are shown in Fig. 1. readYAMLParameters.py is a Python-based code adapted from the previous CsI data release from thecollaboration [2] which takes in the YAML file
LArParametersAnlA.yaml and prints out the name and valueof each entry to the command line.
5. Comments on the use of this release
The organization of this release is intended to facilitate an analysis with the same strategy as thatdescribed in Ref. [1]. An alternative analysis with a different signal hypothesis could proceed with thefollowing steps:1. Prepare alternative signal hypothesis:(a) Generate alternative hypothesis event with a given “true” nuclear recoil (nr) energy: E nr,true (keVnr).(b) Use included quenching factor to convert to true electron-equivalent (ee) energy: from E nr,true (keVnr)to E ee,true (keVee). 5 ) m ( trig t SS - B a ck g r ound S ub t r a c t ed E v en t s DataTotalCEvNSBRNSyst. Error
Reconstructed Energy (keVee) F Figure 1: Projection of the best-fit maximum likelihood probability density function (PDF) from Analysis A on t trig (left),reconstructed energy (center), and F (right) along with the data. The example script provided within the data releasedescribed in this section creates these projections which replicate Fig. 4 of Ref. [1] (c) Use included energy resolution to convert to reconstructed (reco) ee energy: from E ee,true (keVee)to E ee,reco (keVee).(d) Create a 1D E ee,reco distribution of the alternative hypothesis (pre-acceptance correction).(e) Apply included efficiency curve to produce accepted events E ee,reco distribution (post-efficiencycorrection).(f) Then use included CEvNS PDFs to determine F and timing distributions for each E ee,reco bin.The result will be 3D PDF for signal events.2. Use provided BRN, steady-state backgrounds 3D PDFs and add to predicted signal.3. Use provided binned data with appropriate likelihood procedure to find best fit parameters for thealternative hypothesis and adjusted BRN, SS normalizations. Note that the overall number of BRN,SS events are not fixed but variable/constrained as reported in Sec. 2.4. Use systematics as reported in Tab. 3 to run a set of alternative fits that allow an extraction ofsystematic errors on any alternative fit parameters.Notes: • The PDFs are normalized to the initial CV predictions from Ref. [1] and a new fit should allow themto vary subject to constraints listed in Tab. 2. The CEvNS PDF was allowed to float.
6. Citing this release
If you make use of this data release in your work, the COHERENT Collaboration requests that you citeboth [1] in addition to the Zenodo posting of this dataset. Suggested formatting for the Zenodo citation isgiven below:D. Akimov et al. (2020). COHERENT collaboration data release from the first detection ofcoherent elastic neutrino-nucleus scattering on argon[Data set]. Zenodo. DOI: 10.5281/zen-odo.3903810. arXiv: . References [1] D. Akimov et al. (2020), .[2] D. Akimov et al. (COHERENT) (2018), .[3] D. Akimov et al. (COHERENT), Science , 1123 (2017),1708.01294