PoS(ICRC2017)228 on ac http://pos.sissa.it/ and Yuanpeng Wang ac flux of cosmic rays in the SAA, the collected data , Chuan Yue a ICRC2017 scientific analysis. Based on the data from DAMPE, we improve , Jingjing Zang a pre-defined SAA period can be saved for normal data taking comparing with a typical , Xiang Li defined by the space weather forecast before launch. ab ∗ definition of SAA with more precise determination of the boundary. We found that about 30% [email protected] polygon time in the within SAA are not used for most the Atlantic Anomaly (SAA). Due to the high The DArk Matter Particle Explorer (DAMPE) can operate properly while crossing the South Speaker. ∗ Copyright owned by the author(s) under the terms of the Creative Commons c Bexco, Busan, Korea 10–20 July, 2017 35th International Cosmic Ray — Conference 230026, China E-mail: Academy of Sciences, Nanjing 210008, China Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). Determination of the South Atlantic AnomalyDAMPE data from School of Astronomy and Space Science, University of Science and Technology ofUniversity China, of Hefei, Chinese Academy of Sciences, Beijing, 100012, China Wei Jiang Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese behalf of the DAMPE collaboration c a b PoS(ICRC2017)228 500 km Wei Jiang ∼ , e.g.]. The 5 , 4 , 3 . But such a kind of 2 ]. In this case, DAMPE keeps normal 7 , 6 ] was successfully launched on December 2 , 1 2 ] has already briefly defined the general map of the 8 ], which is believed to be an essential reason of failures of 4 , 3 . And it travels through the SAA about 7 times a day. The energy ◦ 97 ∼ , the trigger rate has a periodic trend of high rate at polar and low rate near equator, however, Before launch, the SAA was already measured by many experiments [ The DArk Matter Particle Explorer (DAMPE)[ 1 SAA region for the requirement of the whole project of DAMPE, seen in Fig. it goes a sharp rise betweenare about defined 20 as degrees SAA and periods, 40we identified degrees southern by fit latitude. the these clear These inflection typical inflection pointsin rises points and of of the out the trigger the trigger rate. SAA. rateduring Thus Therefore, over these the time periods, region to hence of determine the theexit the when detected SAA SAA is data the can defined and satellite be as excluded live passes for the time data positions between analysis. where when the the satellite satellite is enter and 17th, 2015 from the Jiuquan Satelliterays Launch in Center. a DAMPE measures very cosmic wideof rays energy dark and range gamma- matter for particles. theVan study Allen Due of radiation to high belt the energy dips non-concentricityregion. astrophysics down of as to The the well 200 fluxes Earth as km of andmagnitude the in larger trapped nature its altitude than proton magnetic in other and dipole, the areassome electron the [ South satellites. in Atlantic Anomaly the DAMPE (SAA) radiation iswith belt operating an around can inclination sun-synchronous reach of orbit twoof at orders trapped the of proton altitude in of the SAApart is of extremely them low is relative to blockedthe DAMPE’s by electronic sensitive energy shield components range. of of Most DAMPE satellite.without survived obvious under The performance such simulations degradation environment and and ofoperation life ground in high-energy lost beam SAA, particles [ where tests the show intensiveSo that particle even hits though will DAMPE dramatically can affect operate thebe normally electronic used in readouts. for the SAA, most the scientificdata data analyses of acquired DAMPE and in to the this develop region events a cannot need method to to precisely be determine tagged. the boundary Thus of2. we the SAA. use SAA the determination recorded space weather forecast made by theChinese Space Academy Environment Prediction of Center, Sciences National using Space Center, AP-9[ definition is not suitable for data analysis,result because that it too is much just a observed rough timeof and will DAMPE, conservative be estimation we as wasted found a when that we the analyzethe trigger the rate particle with data. flux a During low in the threshold operation space,This of trigger the thereby top rate providing layers is a can too directly goodeach high reflect 4 and to seconds simple generate by a way every counter event, to andFig. and transmitted identify it to the the is ground SAA recorded as region. as the housekeeping the data. count As of is the shown in rate for SAA determination 1. Introduction PoS(ICRC2017)228 Wei Jiang gives the comparison 3 400 boundary points of the determined SAA, ∼ , in which the trigger rate shows a sharp rise 2 3 at the altitude close to DAMPE, the size and particle fluxes of the SAA ] show that the location of the maximum particle density in SAA drifts at 1 − 10 , yr 9 · ◦ 4 . The trigger rate during a period when the satellite crosses the SAA 4 times. Black line is the rate The map of this trigger rate is plot in Fig. in the SAA region.smaller than From that this predicted map, bythe we the efficiency find space for that weather data the forecast analysis,spatial with i.e. previous experiments[ AP-9. determined about SAA Thus 30% region it of is obviously the improve AP-9-defined much SAA period is saved. Some a rate of about 0 vary with the solar cycle and geomagneticmeasurement activities to as the well. SAA, Since the DAMPE doesn’t determinedof have SAA month so by consequently. precise DAMPE During a should month, not we change can a get lot at a time-scale thus we can fit the boundary for each month to monitor its variation. Fig. Figure 1: before SAA rejection. As theand blue bottoms line are is equatorial labeled regions. byline Red latitude, is line shifted it is down is the 20000 clear rate manually. after that SAA top rejection. platforms are To make polar a regions comparison, the3. red SAA map among the determined SAAdetermined region SAA in varies the little. first It’sthe the 3 SAA result months of itself. in the 2016, stability Asvariation of in is of both the which applied, this SAA the the determination is boundary method method minimized. and of can the update the SAA in real time, so the effect of the SAA determination PoS(ICRC2017)228 Wei Jiang ]. 8 4 for trapped proton flux above 10 MeV predicted by the AP-9[ 1 − s 2 The trigger rate variation with geographic latitude and longitude. The red solid line is labeled as Comparison of the determinate SAA region among 3 months. The polygons are the fitted bound- − cm Figure 3: aries. It can be found that the boundary changes little over time. Figure 2: the SAA boundary fitted byabout the 1 data from Jan. 1st to Dec. 31st, 2016. The black solid line is the contour SAA determination PoS(ICRC2017)228 ). (2014) Wei Jiang 25 1706.08453 (2012) 4. (arXiv: 203 Nucl. Sci. Tech. , (2009) 193-219. 32 , (2009)125. Astroparticle Physics 281 Astrophysics. J. Supp. (2014) 599-613. 5 Astropart. Phys. (2013) 579-615. 37 , 179 , (2016) 116101. 40 (2014) 550. , 34 , (2008) 466C. 37 cosp Experimental Astronomy Space Science Reviews Chin. Phys. C. Earth and Planetary Science Letters Chin. J. Spac. Sci. 010402. This method for identifying the SAA region is directly based on the cosmic-ray flux in space. The DAMPE mission is funded by the strategic priority science and technology projects in [1] J. Chang, [2] J. Chang et al. [DAMPE collaboration], submitted to [9] F. Fürst, et al., [6] S. S. Gao, C. Q. Feng, D. Jiang, S. B. Liu, Z. G. Zhang, K. Xi, & Q. An. [3] A. A. Abdo, et al. [Fermi-LAT collaboration], [5] M. Casolino, et al., [7] F. Zhang, et al. , [8] G. P. Ginet, et al. [4] M. Ackermann, et al. [Fermi-LAT collaboration], By applying it, we cangood dynamically events discard as the possible, "bad"future, thereby data based in improving on this the the method, SAA efficiency the region for variations and of analysis. SAA keep can as potentially As many be time studied. 5. goes Acknowladgement on in the space science of Chinese Academy of Sciences.the In National China Key the Research data and analysis Development was ProgramBasic supported of Research in China part Program (No. by of 2016YFA0400200), National Chinathe (No. 100 2013CB837000), Talents Program NSFC of Chinese (Nos. Academyand 11525313 of Sciences, and Strategic the 11622327), Astronomy Priority Joint Research Grant (U1631111), verse" Program (Grant of No. the CAS XDB23040000).by “Multi-waveband the Gravitational In Swiss Wave Europe National Uni- Science the FoundationPhysics activities (SNSF), (INFN), and Switzerland; Italy. the the National data Institute analysis for Nuclear are supported References SAA determination 4. Summary [10] R. Campana, et al.