PoS(ICRC2017)1089 , c , d http://pos.sissa.it/ 1 keV/nuc and d ∼ , A. W. Labrador d , E. R. Christian c , R. A. Leske , G. A. de Nolfo c b , and T. T. von Rosenvinge c , A. J. Davis , M. H. Israel c b , E. C. Stone c , W. R. Binns Fe and a number of stable “ultraheavy” elements with atomic numbers in the a 60 ∗ , A. C. Cummings c 30 to 40. In addition, elemental energy spectra have now been measured over a sig- , R. A. Mewaldt = b Z mark.e.wiedenbeck@jpl.nasa.gov 1 GeV/nuc, was launched in August 1997 into an orbit about the L1 Lagrangian point 1.5 mil- Speaker. The Advanced Composition Explorerprecision (ACE), measurements which of carries the instrumentation charge for and making mass high- of energetic nuclei between nificant fraction of two solar cycles,modulation thereby of enabling galactic studies cosmic of rays. the time dependence of the solar ∼ lion km sunward of thewide Earth. range of From studies in this galacticare, vantage and for point, heliospheric the ACE physics. most collects The part, data ACEmission spacecraft continuing that duration, and to are which instruments perform is used already very for almostwas well a nominally an and required order to of of extend ACE, magnitude has their greatervisioned made data than when it the sets. the possible mission two to was The years address proposed. that science long Cosmic In topics Ray this beyond Isotope paper those Spectrometer we en- (CRIS) address is several topics contributingCRIS to in has which the been ACE’s area of able galactic to cosmic makedioactive radiation. nuclide measurements of extremely rare species,range including the primary ra- ∗ Copyright owned by the author(s) under the terms of the Creative Commons NASA / Goddard Space Flight Center, Greenbelt, MD 20771 USA Jet Propulsion Laboratory, California Institute ofWashington Technology, Pasadena, University, CA St 91109 Louis, USA MO 63130California USA Institute of Technology, Pasadena, CA 91125 USA c Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). E-mail: 35th International Cosmic Ray Conference —10–20 ICRC2017 July, 2017 Bexco, Busan, Korea C. M. S. Cohen K. A. Lave M. E. Wiedenbeck Recent Results from the Cosmic RaySpectrometer Isotope on NASA’s Advanced Composition Explorer c a b d PoS(ICRC2017)1089 M. E. Wiedenbeck shows a photograph of the 1 ]. Figure 1 2 Photograph of the ACE spacecraft at APL after instrument integration and before installation The highest energy measurements are made by the Cosmic Ray Isotope Spectrometer (CRIS) The Advanced Composition Explorer (ACE) mission was developed in the 1990s under NASA’s ], which is used for the study of galactic cosmic rays (GCRs) that arrive near Earth with energies 2 Figure 1: [ of thermal blankets. Onenergetic orbit, particles the are top mounted, deck, facesFigure where generally from instruments sunward. the used ACE The for Science CRIS Center studying instrument Picture the Gallery. is solar located wind on and a solar side panel. spacecraft during integration at the Johns Hopkins Applied Physics Laboratory (APL) in 1996. Explorer Program to carry outcomposition detailed of investigations energetic of particle populations the accelerated elemental,Galaxy. at isotopic, the The and Sun, mission, in charge-state its the scienceries heliosphere, objectives, and of and in articles our its published payload shortly of instruments after are the described 1997 in launch a [ se- ACE/CRIS Highlights 1. Introduction PoS(ICRC2017)1089 . 0 E ) and shows E 2 ∆ versus E plot (including ∆ 0 E M. E. Wiedenbeck versus E ∆ ) has been employed in numerous E gives an overview of the variations seen in solar ]. Right: sample CRIS versus total- 3 3 3 dx / dE ]. . CRIS consists of four stacks of silicon solid-state detectors (two 4 2 500MeV/nuc. A schematic cross section of the instrument is shown , ) that are used for making measurements of energy loss ( 3 ∼ 2 50 to ∼ ) of nuclei that stop in those stacks. The right-hand panel in Figure technique (also called 0 0 E E Left: cross section of the CRIS sensor system. Blue (red) arrow indicates the trajectory of a typical versus E ∆ The long period of data collection has also allowed the accumulation of statistically meaning- Although ACE was developed for a prime mission of 2-year duration, the design carefully The long exposure time has enabled a variety of ACE studies that go beyond what was planned The energy coverage for stopping particles is determined by the joint requirements that they ful samples of some rare elements and isotopes that led to new results on cosmic-ray composition. energetic particles (SEPs), ACRs, and GCRs over the course of the mission. Figure 2: stopping (penetrating) particle. Figure adapted from [ residual energy ( stacks are visible in Figure avoided compromises that mightwriting, unnecessarily ACE limit has the been mission operatingperform well. life for In just time. particular, over the 20 CRIS At response years the has and remained time essentially most unchanged of offor since this the launch. the instruments prime mission. continue to Withbeen nearly possible to two trace full how solar the solar cyclesrays modulation of (ACRs) of responds both data to galactic (one solar cosmic Hale rays variations. and magnetic Figure anomalous cycle), cosmic it has ACE/CRIS Highlights generally in the range in the left-hand panel of Figure a sample of CRIS data illustrating how particle species are resolved on a plot of approximate corrections for incidence angle) showing separation of element and isotope tracks. This penetrate to the second detectorE2 (E2) and in E8 in one that of stackrings the and that stacks do surround not and detectors trigger that E2 a through they backscintillating E7. stop anticoincidence optical At detector somewhere fiber the (E9) hodoscope between front or (SOFT) of any sensorof the of that silicon particles the provides detector guard incident measurements stacks, on of CRIS has the thosepenetrated a trajectories stacks in and the allows stack precise detectors.composition corrections can for be Some found the examples in the of [ amount CRIS of data silicon on GCR elemental and isotopic instruments designed for studying energetic particles in space. PoS(ICRC2017)1089 ] is dominated by M. E. Wiedenbeck 5 emission with a half-life of − β Ni 59 4 Al, which have been extensively studied in cosmic 26 Fe and Fe undergoes decay by Be or 60 60 10 ] have reported the first observations of a surviving primary radionuclide in 6 Fe provides strong evidence that there is at least a component of the cosmic rays 60 shows a mass histogram containing Fe events measured during the first 17 years of the 5 Energetic particle intensity variations measured over 20 years by instruments on ACE. Upper shows how the fluence of GCR Fe collected by CRIS in three different energy intervals has Fe is not produced in significant abundance by fragmentation of heavier nuclides. Thus, 4 60 Figure Binns et al. [ large SEP events (intensitymic spikes) rays during during the solar maxima minima.Spectrometer of Lower (CRIS) solar panel: is cycles 426–466MeV/nuc dominated 23penetrated iron by and to measured galactic the 24 by cosmic inner the and heliosphere. rays Cosmic by that Ray anomalous have Isotope cos- undergone solar modulation as they Figure 2.6 Myr. Unlike radionuclides such as rays, any observed ACE mission. Besides the isotopes withnew, masses high-statistics 54 sample through reveals a 58, peak which centered were around previously mass studied, 60 this that contains 15 events. Because the galactic cosmic rays. The isotope arriving near Earth that has been synthesizedlonger and than ejected several from Myr. stars on a time scale not significantly grown over time. Now, in 2017, weaccumulated are fluence in increases the most early rapidly. part Bysample of the should another time solar exceed of that minimum the period obtained solar when during the cycle the 25 prime maximum, mission the by GCR more than an2. order of Primary magnitude. Radioactive Nuclides: Figure 3: panel: 15.6–21.0MeV/nuc oxygen measured by the Solar Isotope Spectrometer (SIS) [ ACE/CRIS Highlights PoS(ICRC2017)1089 Fe Co. and 58 ) for 59 5 X detector and a E M. E. Wiedenbeck ∆ shows measured 6 Fe are not a background due to 60 emission with a half-life of 45days, Co with the high-side tail on − 57 β Fe. They also carried out numerous tests 58 Fe abundance. The clean separation from the 5 60 detector, which results in displacing an event toward 0 7, enabling studies of some very low-abundance elements and E ∼ Fe event per year is sufficient to give a well-defined mass 60 Fe, which decays by 59 Fe events are a sample of the same arriving cosmic-ray population as 60 by comparing the low-side tail on 5 ] pointed out that the CRIS Co mass histogram (right-hand panel of Figure 6 Galactic cosmic ray fluence measured in three energy intervals by CRIS from the start of the ACE In order to have confidence that the events identified as coordinate displacements (proportional to tangents of the corresponding projections of particle Co, which has an abundance comparable to that of the low-mass side of an isotope track. The left-hand panel of Figure that demonstrate that the the rest of the Fe. this same time period59 has only one event located two mass units above the heaviest stable nuclide, some much more abundantdistributions. nuclide, It we is typical have for looked theprominent mass in distributions tails measured detail with on at CRIS the to thehand have low significantly tails panel side more of of than the Figure on measuredA the mass major high contributor side to of low-sideclosely tails the aligned is peaks, with channeling, as major which can axes causesenergy or be particles loss. planes seen traveling This of in in effect the directions the causescorresponding silicon a right- increase crystal small in to decrease have the in a following the slightly energy reduced deposited rate in of the peak is possible because the isotope is absent and because measured massBinns peaks et typically al. do not [ have long tails on the high-mass side. Figure 4: mission through mid-2017. Since thecosmic-ray completion sample of has the increased prime by a missionisotopes. factor in 2000, the size of the accumulated of the long-term stability of thethat CRIS allow detectors efficient and electronics rejection andstacks) of multiparameter the backgrounds measurements collection (for of less example,peak than due and one enable to measurement fragmentation of the in surviving the detector ACE/CRIS Highlights Y PoS(ICRC2017)1089 ]. Fe 8 60 , 7 ] would be 6 Fe to leave the 60 M. E. Wiedenbeck Fe peak that has been shifted 56 Fe measurements, one can infer 60 Co tail does not extend below mass Fe was synthesized, the detection of 57 60 65). The pattern clearly demonstrates the . , which shows the calculated locations of 6 25 < 1kpc from the solar system. Z 6 ∼ Fe depends significantly on the interstellar propaga- 56 ]. 6 Fe. Fortunately, the Fe/ 60 60 Fe [ Fe, it is important that the boundary between Fe and Co be 60 can lie close to the high-mass tracks for the adjacent element 60 Z 1. For technique employed in CRIS, response tracks of low-mass isotopes for 0 − E Z Fe were produced near the solar system and transported to us without spending 60 versus 53.5 should overlap with ). It is conceivable, however, that the one event in the Fe mass histogram above mass E ]. The red curve overlaid on the black histogram is a copy of the ∼ 5 ∆ 6 Left panel: histogram of calculated masses of cosmic-ray Fe nuclei measured with the ACE/CRIS The derivation of the source ratio In addition to setting a limit on how long ago the arriving In the 54.5 (Fig tion model, with longer propagation timesobserved requiring amount larger of source this abundances radionuclide of applicable after if decay. the Our simple leaky-box calculation [ Combining the diffusion coefficient with thethat time the scale nucleosynthesis from occurred the no more than 60.8 might actually be spillover from Co.assigned to This possibility the was number taken of into detected account in the uncertainty tracks for selected Fe andCo Co mass isotopes of in one of the CRIS detector combinations, indicates that a incidence angles) measured for Feside nuclei tail on traversing the the distribution SOFT of calculated hodoscope charges and ( falling in the low- upward by 4 mass units andregion of scaled the down plot. to have Right an panel: area histogram corresponding of to calculated the masses number of of cosmic-ray Co events in nuclei. the ∼ this radioisotope also provides a constraint onoccurred. the distance to Estimates the of sources where theGalaxy the nucleosynthesis diffusion have coefficient been that derived controls from the measurements transport of of abundances cosmic of rays secondary in radionuclides the [ Figure 5: instrument [ importance of channeling in causing this tail. with atomic number ACE/CRIS Highlights appropriately placed so that theof low-side the Co Fe tail distribution. will The not right-hand contribute panel background of on Figure the high side an element of atomic number PoS(ICRC2017)1089 Ni 59 ] as having 10 Fe and spends a M. E. Wiedenbeck 56 Fe being measured 60 tracks for selected stable 0 E – E ∆ Co was interpreted [ ], pure ec nuclides that are ejected 59 Fe that CRIS is detecting. 11 60 65 charge units). These events fall preferentially . Ni-containing ejecta by a shock wave from the 25 59 Ni). 7 < 60 Z Ni, with a small admixture of secondaries produced 59 Co) and for unstable nuclides that would overlap with the 59 Si detectors. Right: calculated i yr) in the arriving cosmic rays indicates a long time delay, Co) superimposed on a sample of CRIS data. Typically, multiple 4 Co, 54 111 57 ]. This nuclide is radioactive and its only significant decay mode 10 Fe detected in deep-sea sediments and in samples of the lunar h 60 × 10 Co, Fe, 6 Ni would also be absent if this nuclide were not produced and ejected . 53 60 Fe would have decayed. 59 60 Fe, 56 ]), which are thought to be due to deposition of ejecta from a recent, nearby 9 ] pointed out the possible association of the cosmic-ray 6 , taken from one of the earliest CRIS publications, shows no evidence for surviving 7 Left: two-dimensional distribution of incidence directions for Fe nuclei in the extreme low- yr, incompatible with the acceleration of the However, we noted that Binns et al. [ Figure 5 10 Fe is produced with the same spatial distribution as stable nuclides such as Ni in the arriving cosmic rays [ Ni (laboratory half-life of 7 Fe track if they were present ( significant amount of time diffusingfraction in of the the accelerated halo like secondary radionuclides, then a much larger by the spallation of heavier nuclides (primarily in significant abundance from the supernova. Plots illustrating our interpretation of the CRIS significant amounts of time60 in the galactic halo or in other distant regions. On the other hand, if mass measurements from this type ofresolution analysis and are background compared rejection. for consistency and averaged to optimize mass and long-lived nuclides60 ( in CRIS with recently reported regolith (reviewed in [ dominantly been produced by the decay of along low-order crystal planes of the supernova—perhaps the same supernova that produced the 59 is orbital electron capture (ec). As noted by Soutoul et al. [ in supernova explosions can provide anacceleration. indication Until of the they time aredecay, delay accelerated, but between these after nucleosynthesis acceleration nuclei and 59 the will ec have decay electrons is attached not and possible be and able they to become stable. The absence of Figure 6: side tail of the distribution of calculated charges ( > ∼ same supernova that synthesized this material. The observed ACE/CRIS Highlights PoS(ICRC2017)1089 Ni 59 ] reproduced with M. E. Wiedenbeck 10 Ni (ordinate) and the 59 Ni on the time delay between 60 Ni, which decays only by orbital 59 Co/ 59 Co, is clearly present. Figures adapted 59 Ni and 60 Ni was most likely due to decay of 59 Ni/ 59 8 ] that more recent supernova nucleosynthesis calculations Ni have reopened the question of whether the lack of cosmic- 13 59 . Using nucleosynthesis-yield calculations that were available at the 8 CRIS mass histograms for Ni (left) and Co (right). The isotope Left panel: calculated dependence of the ratios ], we concluded that the lack of cosmic-ray ]. 12 Ni clearly indicates a long time delay. Further theoretical work to reconcile the discrepant 10 It has recently been pointed out [ Ni (solid lines). The dashed lines indicate the calculated contributions of secondary cosmic rays to the 59 ] that found much lower yields of 59 14 permission of the AAS. rather than to lack of production and ejection of this nuclide. nucleosynthesis and acceleration (horizontal axis)as and on the fractiontwo of ratios. the The mass-59 hatched material regions areregions synthesized compatible of parameter with space the defined CRIS by isotope thetime measurements. fraction delay of Right between mass-59 nucleosynthesis panel: material and Allowed synthesized acceleration as (abscissa).only The a cross-hatched two region standard takes into deviation account also uncertainty includes in a the 50% measured uncertainty abundances in while nuclear the fragmentation diagonally-hatched cross region sections. Figures from [ Figure 8: results are shown in Figure ray supernova nucleosynthesis results is now needed. Figure 7: time [ [ ACE/CRIS Highlights electron capture, is absent while thefrom daughter [ product of its decay, PoS(ICRC2017)1089 Zr. 32. 40 ) has ] that ' 4 Z 15 , 18 ] and shows 15 M. E. Wiedenbeck elements, further analysis Z Ni and exploratory measurements 28 40 measured by CRIS (blue squares) and ≤ Z ≤ 40, the energies deposited in some of the CRIS Zr (Binns et al., in preparation). The left panel of = 9 40 Z elements. Z compares preliminary cosmic-ray source abundances derived from 9 ]. 15 ]. In this plot, refractory and volatile elements are shown in different ] and freshly synthesized massive star material (MSM) ejected by stellar 17 16 shows, as a function of element mass, ratios of the GCR source abundances derived 10 Zn. The additional exposure made possible by the long mission duration (Fig. Left: histogram of calculated charges measured by CRIS for ultraheavy elements up through shows a charge histogram for the UH region. Besides obtaining increased exposure, we 30 9 Figure The exposure of the CRIS instrument over the baseline ACE mission was planned to allow The right panel of Figure ] with a somewhat different mixing ratio, organizes the data significantly better than if the GCR 18 by SuperTIGER (red circles) [ Figure 9: Right: comparison of composition in the charge range 30 colors, as are log-log fits to[ these two element groups. This typesource of composition comparison, is previously compared used with in pure solar-like composition. It has been argued [ allowed us to extend composition studiesFigure up to the CRIS data withthat published there values is from reasonable the agreement for SuperTIGERof most the balloon abundance elements. experiment corrections For and [ the theiris highest- uncertainties published. may lead to adjustments when the CRIS work from the CRIS datasystem-like to material abundances [ in a population of matter consisting of a 94:6 mix of solar- winds and supernovae [ have also significantly improved the rejectionfor of a backgrounds. tiny fraction Errors of in theregion the because Fe-group measured of events trajectories the can large lead abundance to ratio significant between contamination the of Fe-group the and UH the element elements above precise measurements of elements and isotopes up through ACE/CRIS Highlights 3. Composition of Ultraheavy (UH) Cosmic Rays through detectors start to saturateadjust the for pulse-height loss analyzers. of Uncertaintiesderived events abundances in due for the to these highest- corrections this applied saturation to contribute significantly to the uncertainties in the A careful study of thesebackground effects events. For has elements allowed approaching us to identify and eliminate a large fraction of such PoS(ICRC2017)1089 M. E. Wiedenbeck 10 shows examples of Fe energy spectra measured at the 11 Ratio of GCR source abundances derived from the CRIS data to abundances calculated for an The GCR intensities measured for major heavy elements by CRIS have sufficient statistical lowest and highest levels ofalso solar in modulation May 2017, encountered shortly thusmodulation, before far is this during shown writing. from the September ACE Avide 2013. mission fourth a set and The reasonable of modulation fit data, at toearly with that 1980s. spectra an time The at intermediate was HEAO higher level found data of provide energies towhere an also measured solar important pro- by modulation constraint the does on the not HEAO-C2shown spectra experiment cause were above obtained in large a from variations few the a GeV/nuc over leaky-box-modelthe the calculation interstellar solar of medium cycle. equilibrium followed cosmic-ray by The intensitiesmodel a curves in that solar-modulation that includes calculation are diffusion, using convection, a and spherically adiabatic symmetric deceleration. The ACE spectral measure- Figure 10: 4. Solar Cycle Variation of GCR Energy Spectra accuracy to allow energy spectra torotations. be The derived over left-hand time panel scales of as Figure short as individual 27-day solar admixture of 6% massive starto material have (MSM) solar-like with composition. interstellar Lines mediumfor are material volatile log-log elements. (ISM), fits which done is individually assumed to the data points for refractory and ACE/CRIS Highlights this organization involving a SS–MSMfractories mix relative and to a volatiles supports greater the enhancementwhere idea of refractories that are the cosmic found rays GCR in are source grains accelerated of in and re- OB volatiles in associations the gas phase. PoS(ICRC2017)1089 M. E. Wiedenbeck ] should improve values obtained for 20 φ ]. 3 ]. Right: time variation of the solar 21 ] and AMS-2 [ 19 ), the CRIS instrument also records signals from 2 11 shows the time dependence of the 11 , that is calculated as described in [ φ values at a given time show a systematic difference that can be as large derived by matching CRIS spectra of the type shown in the left-hand panel with φ φ Left: CRIS measurements of GCR Fe energy spectra from four selected 27-day time periods, 100MV. These differences may be associated with the difference between the energy inter- In addition to measuring signals from heavy nuclei that stop in the CRIS detector stacks (illus- A weakness in the CRIS modulation studies carried out to date is that the energy spectra in The right-hand panel of Figure ∼ calculated template spectra. modulation parameter Figure 11: including times with the minimum andsion maximum to levels of date, solar one modulationduring recent observed the during HEAO time mission the period, in ACE the mis- and early 1980s. a HEAO time data taken period from with [ modulation comparable to that experienced particles that penetrate an entireetrating detector particles stack, have as been illustrated recorded, by at a the lower trajectory priority, in since red. the beginning These of pen- the ACE mission, trated by the trajectory shown in blue in Figure five different elements overin the detail, entire but ACE derived mission to date. The five curves track one another this situation. vals over which the elementsWith are more measured sophisticated and/or differences modeling, inheliospheric it the phenomena may that mean control be mass-to-charge solar possible ratios. modulation. to exploit these effects tothe investigate region the above a GeV/nucCRIS. are The not HEAO measurements as are wellof precise the constrained CRIS but as measurements. do at New, not precise therange come measurements that lower from of are energies heavy-element the starting measured spectra same to in with time become the period available GeV/nuc from as PAMELA any [ as ACE/CRIS Highlights ments are at a lowresponding enough to energy major so modulation that changesout as they through can vary the occur significantly heliosphere. when overspectra large the Each from CME-driven solar measured shocks this cycle, propagate spectrum model as was thatwith well compared differ a as “modulation only with parameter”, in a the library assumed of modulation template level, which we characterize PoS(ICRC2017)1089 M. E. Wiedenbeck . 12 and the second derivative, technique used for stopping have different dependences dx (right) derived from a standard / E dx / dx dE / dE dE . It may be possible to improve the ). This is used in conjunction with the dx and 2 Fe that produces high-energy knock-on / versus total- E 26 versus dE dx 2 / curves for different elements, as shown in the dx / E dE - E 12 2 technique is not directly applicable for penetrating d dx / 0.2) there is overlap between tracks, as is most easily E - < ∼ dE dx Cr, where there is an enhanced density of points. Geant4 / 24 , we compare the energy losses in detector E1, at the front of (left) and 2 dE , as illustrated in the right-hand panel. In the high-energy region E dx ◦ / 0 E = 2 . The d θ versus 12 dx / illustrates the application of this analysis technique to CRIS angle-selected dE 13 Plots of to account for the angular variation of the thickness of silicon penetrated. The left-hand , also have different velocity dependences, one can develop a similar analysis method 2 θ dx To obtain a measure of In order to obtain better constraints on the energy spectra of cosmic-ray elements near the / E 2 d based on these two parameters, as shown in the right-hand panel of Figure at the bottom of the plot (ordinate values electrons that penetrate into detectors deeperThis in region the is stack also and increase affected the by energy the deposited relativistic in E8. rise in penetrating-particle data collected during 2009.are well The resolved element over much tracks of at thedifferent plot, a angles. but given there A is angle simple a correction of for spread incidence incidence amongthe angle the tracks can tracks onto be for the applied a to track given approximately element for map at all of seen near the bottom ofsimulations the have track shown for that this is due to relativistic Figure 12: particles because the total energy is not measured. However, since heavy-ion range-energy relation illustrate thepenetrating-particle approaches data used sets. for resolving elements in the stopping- and the stack, and E8, nearsum the of back the of energies the depositedby stack in sec (see all Figure of the stack detectors from E1 through E8, which we divide panel of Figure energy where the intensity maximaadvantage occur, of these we penetrating-particle are data. developing The a new analysis technique that takes ACE/CRIS Highlights but to date they only been considered in a few exploratory studies. particles takes advantage of the fact that the quantities on particle velocity, which separatesleft-hand the panel of Figure PoS(ICRC2017)1089 . ◦ 0 13 = ; red, ◦ θ –7 ◦ in abscissa. θ M. E. Wiedenbeck 13 values for events falling in the upper part of Figure M / E correction applied other than the explicit division by sec θ have been normalized to match the extrapolation from the highest energy , its incident energy per nucleon can be calculated from the range–energy -dependent corrections applied to approximately map all of the data onto the . Left: no 13 14 ◦ θ events, which are assigned the highest priority, but only a fraction of the lower- –47 ◦ Z shows examples of combined CRIS stopping- and penetrating-particle energy spec- 14 Scatter plots constructed using parameters that produce resolved element tracks for penetrating ; blue, 43 ◦ Once a particle’s atomic number has been identified from the location at which the event falls Figure –31 ◦ relation using as inputs the totalin thickness penetrated that in thickness. the detector stack Thismass and calculation can the energy be depends deposited assumed on to the bea that particle’s mass-dependent of mass. error the in most As abundant the isotope derived a of first the element, approximation, but the that will introduce priority penetrating events. Counts offor numbers each of priority events and detected can andare be telemetered still used are working to on maintained developing correct and for validatingthe these the corrections, spectra events the in that penetrating-particle Figure could portions of notpoints be in transmitted. the Since stopping portion. we tra for O and Fe at solarof minimum penetrating (2009). particle The calculation events of detectedof absolute requires intensities these from a the events correction numbers to forstopping, the inefficiencies high- ground. in the The transmission bit-rate assigned to CRIS is sufficient to transmit all of the resolution in this region byexpected comparing from the deposited-energy energies calculations. measured in the other detectors to the pattern on a plot like Figure 29 Right: same data with tracks. Ultimately, it will be necessary tomation, correct which derived is energy available spectra from using the isotopic stopping-particle composition data. infor- Figure 13: nuclei. Energies are in MeV. TheEvents data are plotted included were collected from by three CRIS narrow during ranges the of solar incidence minimum year angle, 2009. as indicated by color: black, 0 ACE/CRIS Highlights PoS(ICRC2017)1089 M. E. Wiedenbeck 14 Fe. Fe; 2) providing further evidence that cosmic-ray source 56 60 Fe/ 60 Points: preliminary energy spectra of Fe and O measured by CRIS for the solar minimum year We thank G. Morlino and V. Ptuskin for helpful comments on the application of propagation The ACE spacecraft is capable of operating well into the maximum of solar cycle 25 and is For the past 20 years, data from the CRIS instrument on ACE have been providing precise, models to derive of the source ratio Acknowledgments expected to provide measurements that willSolar be Probe important and for ESA’s interpreting Solar data Orbiter from missions,as NASA’s which Parker continuing are to scheduled to monitor be space launched weather in in 2018, the as near-Earth well environment. composition is well represented by a mass-dependentconsisting of fractionation a of mix a of parent massive population star of materialare with matter old, extracted solar-like ISM with from which efficiencies refractoryvolatile that elements elements; are and enhanced 3) determining bysolar the cycles about using time a energy variation spectra factor of of solar of multiple heavy modulation four elements. over relative nearly to two those full for Figure 14: near-Earth measurements of galactic cosmic-rayenergy elemental spectra and near isotopic the composition, intensitytime, and a maximum. also surviving of primary Recent radionuclide, advances include: 1) detecting, for the first 2009. The stopping points (filledpenetrating circles) points are (open from circles) level are 2 derived using datathe the available penetrating new from analysis spectra technique. the was ACE The adjusted Science absolute toa normalization Center. approximately common of The match scale the factor extrapolation for ofparticle both the intensities O stopping is and spectra presently using Fe. being worked The on derivation by of the the CRIS absolute team. normalization for the penetrating 5. Summary and Conclusions ACE/CRIS Highlights PoS(ICRC2017)1089 , , C , , 14 591 , Space Sci. , A86, , ApJ 588 , , Mn, and 54 M. E. Wiedenbeck A&A Cl, , 36 Fe in Supernova Dust to Al, 60 26 86, Nos. 1–4, 1998. Be, 10 The Advanced Composition Explorer , L61, 1999. , 768, 2001. 523 563 , , , 15, 2001. , 21, 2013. , 148, 2016. Ni in the Cosmic-ray Flux 99 59 , 753, 1978. ApJ , 764 , ApJL 831 , Cosmic-Ray Propagation and Interactions in the , , 219 , 181, 1995. , 15 Co Space Science Reviews ApJ ApJ , 101 59 Co and , , ApJ 59 , Zr Fe Nucleosynthesis-Clock Isotope in Galactic Cosmic Rays 40 Time Delay between the Nucleosynthesis of Cosmic Rays and 60 ApJS , 285, 2007. Ni and , Space Sci. Rev. Radioactive Iron Rain: Transporting , 59 57 , , 117, 2013. The Evolution and Explosion of Massive Stars. II. Explosive 770 Fe through , Nucleosynthesis and Remnants in Massive Stars of Solar Metallicity Abundances of , 48, 2016. Pre-supernova Evolution of Rotating Solar Metallicity Stars in the Mass 26 Constraints on the Time Delay between Nucleosynthesis and Cosmic-ray The Origin of Primary Cosmic Rays: Constraints from ACE Elemental and ApJ 827 , , Measurement of the Secondary Radionuclides Galactic Cosmic Ray Origins and OB Associations: Evidence from SuperTIGER and their Explosive Yields , 269, 2007. Observation of the , 285, 1998. 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