Search for solar neutrons using NM-64 equipment

138 138 SHSH1.4-5 1.4-5 SEARCH NEUTRONS SEARCHFOR FORSOLAR SOLAR NEUTRONSUSING USINGNM-64 NM-64EQUIPMENT EQUIPMENT N.J. N.J.Martlnlc, Mart1n1C,A.A.Reguer_n, Reguerln,E.E.Palenque, Palenque,M.A. M.A.Taqulchiri Taqu1chiri Chacaltaya Cosmac Ray Laboratory, Universlty Chacaltaya Cosm1c Ray Laboratory, Univers1tyofofLaLaPaz Paz M.M.Wada, Wada,A.A.Inoue, Inoue,K.K.Takahasha Takahash1 Instatute Inst1tuteofofPhysacal Phys1caland andChemical ChemicalResearch, Research,Tokyo Tokyo ABSTRACT ABSTRACT TwoTwo years years(1980-1982) (1980-1982)neutron neutronmonltor mon1tordata datafrom fromthetheChacaltaya Chacaltaya(geogra(geographlc °, W68.15°; ph1ccoordanates: coord1nates:N16.32 N16.32°, W68.15°;cutoff cutoffrigadlty: rig1d1ty:13.1GV; 13.1 GV;altitude: altitude: 5,300 a.s.l.) 5,300m m a.s.l.)station stationhashasbeen beenscanned; scanned;thethesampling samplingtame t1meofofthethe12NM12NM64 64neutron neutronmonator mon1toris1S5 5mln. m1n.TheThenucleonic nucleoniccomponent componentincreases increaseshave havebeen been correlated correlatedwith with66 66hard hardX-,X-,gamma-rays gamma-rayssatellite satellitedata datafrom fromsolar solaroragin, or1gin, as asreported reportedby byseveral severalgroups. qroups.WeWepresent presenttypical typicalneutron neutronmonitor monitortlme t1me profales prof1lesofofthe theevents. events.Chree-analysaswas Chree-analys1s wasperformed performeddiscrlminating discr1minatingthe the events eventsaccordang accord1ngats 1tSsolar solarcoordanates. coord1nates.Ground Grounddata datafrom fromsolar solarlimb limblocli loc1i are aremore moreenhanced enhancedatatthe thetame t1meofofthe theonset onsetthan thanother othergeometracally geometr1callyvisivisible bleflares. flares.WeWepresent presentalso alsoChree Chreehlstograms h1stogramsofofneutron neutronmonitor monitorout-put out-put profales prof1lesfrom fromgeometracally geometr1callyinvasible 1nv1sibleevents eventsfrom fromthe theChacaltaya Chacaltayastation. station. I.1.Introductaon Introduct10n The Thesearch searchfor forsolar solarneutrons neutronsusing usingevaporataon evaporat1onneutrons neutronsofofthe thenucleonic nucleonic components componentsofofthe thecosmic cosmicrays raysdetected detectedbybyground groundbased basedinstruments instrumentshas hasled led totoscan scanout-puts out-putsofofhagh h1ghaltitude, altitude,hlgh h1ghcutoff cutoffragadaty r1g1d1tystataons. stat10ns.The Thelow low attenuataon attenuat10nlength lengthofofsuch suchstataons stat10nsmakes makesititpossible possibletotorecognize recognizeadditaoaddit1onal, nal,from fromsolar solarorlgan, or1g1n,neutron neutronenhancements enhancementsone oneas1Sexpected expectedtotoidentlfy. 1dent1fy. OnOnthe thesolar solarsurface surfaceneutrons neutronsare areavailable availableasassecondary secondarypartlcles part1clesofofthe the interact£ons interactionsofofenergetac energet1cnuclea nucle1an1nthe tneba_e vaseofofthe thecorona; corona;also, also,IHIHcaptucapturereofofneutrons neutronsradaate rad1ategamma gammallnes 11nesofof2.22 2.22MeV MeV(Prince (Princeet. et.al., al.,1983). 1983).O-Other therphotons: photons:the the0.5 0.5MeV MeVposltron pos1tronannihalatlon annih1lat1onand andthe theK0nOdecay decayfurnishes furnishes the from theother othergammas; gammas;the thehard hardX-rays X-raysare areproduced producedvla V1abremmsst-@ahlung brems~ahlung fromthe the enrgetic enrgeticelectrons. electrons. WeWeassume assumethat thata asolar solarflare flareis1Srelated relatedwlth w1thsome somekand k1ndofofacceleration accelerationmemechanasms chan1smsfor forelectrons electronsor/and orlandprotons protonsand andother otherspecies; species;and andthat thatneutrons neutrons (or (orthe theenergetic energeticphotons) photons)shall, shall,an1ngeneral, general,follow followthe thetrajectories trajector1esofof the theaccelerated acceleratedparents. parents.The Thelatter latterhas, has,in1ngeneral, general,preferred preferreddarectlons, d1rect1ons, say, say,parallel paralleltotothe thesolar solarsurface. surface.Less Lessenergetlc energet1cneutrons neutronsand andX-rays X-raysmay may bebeproduced producedasotroplcally. 1sotrop1cally. InInthis thisphenomenologicalanalysis phenomenological analysisweweassume assumethat thatthe theneutron neutrongeneratlonis generat10nis impulsive impulsive(typical (typicallife-t_me: life-t1me:= ~ 100 100s)s)and andthat thatatatleast least0.5 0.5ofofthe theneuneutrons tronscan canescape escapethe thesolar solaratmosphere. atmosphere.WeWepresent presentbelow belowstatistical statisticalanalyanalyses sesofof6666solar solarevents eventscorrelated correlatedtotothe theground groundbased based1212NM-64 NM-64ofofthe theChaChacaltaya caltayastation. station. 2.2.Data Datatreatment treatment From Fromthe the6666solar solarevents eventsweweinvestigate,we 1nvestigate, weshow showininFig. Fig.I 1a atypical typicaltame t1me profale prof1leasasseen seenbybythe the5-man 5-m1nChacaltaya Chacaltayamonitor. monitor.The Thesh_rt shQrtsample sampleofof3 3 hours hoursexhibat exhib1tananincrease increasesynchronic synchronicwith withthe theonset onsettlme t1meofofthe thereported reported satellate satel11tedata; data;however, however,notlce not1ceother otherincreases increasesmore moreimportant importantthan thanthe the formerone. one.The Thesagma, s1gma,o,a,ofofthls th1sshort shortsample sampleisis0.3 0.3% % t~n during6 6 former ta_n during hours hoursdata. data.AsAscan canbebechecked checkedononTable TableIII, III,the theparent parentflare flarewas wasa alimb limb one and the onset was on 21:15 of Dec. 23th 1980. It was a short one and the onset was on 21:15 of Dec. 23th 1980. It was a shortlived lived 139 139 SH 1.4-5 ISH .4-5 23-DEC-805-MIN 5-MIN COUNTING 23-DEC-80 COUNTING RATERATE + 1 /' t +* o -- - 1 % 22:00 21: 00 23:00 Fig.!: NucleoniC cCIIpOOent N1-64 hilt profile. The solar ~ ray event IS shCllt .uth a dash. 5 MIN - CHACAL TAYA - DATA 5 MIN - CHACALTAYA _ NM - DATA + .3 % + .3Z I o --- -.3: - .3 7. -I -1 o (hours) 1 I 2 I 2 Fig.2: Chree AnalysIS of tl vIsible 9aIIIU or X- flirts (see Tible III>. Fig.2:The_rH _al_zsire_given 11visible _ lean X- fl_M (seeTable liD. of the ordinates In X ofgamma 6-hour value. The total length The_dmat_ _e gwen m Z _ 6-hour m anvalue. Me total Imgth _ the plotted data II three hours. The onset of the IM!IIt IS shCllt .nth a dash. plott_ _ta is thr_ hours. Me m_t _ t_ event=s_om .=_ a _. 8 flare ( 15 s ) w~th a peak em~sion above 0.3 MeV photons a~cordng to the flare ( 15 s ) wzth a peak emzssion above 0.3 MeV photons aecordzng to the SMM data; the GOES clasif~ton ~s M3. A spec~al feature of th~s prof~le SMM data; the GOES classiflcat_on Is M3. A speczal feature of thls profale is that it appears en enhancement more or less continuous of the mon~tr is that it appears en enhancement more or less continuous of the monltor data before after flare onset. data one one hourhour before and and one one hourhour after the the flare onset. F~g. 2 illustrates a Chree anlys~ of 11 solar events when the sun ~s Fag. 2 illustrates a Chree analyszs of 11 solar events when the sun is above the hor~zn ( see Table III ); the flare locat~n is correlated w~th above the horlzon ( see Table III ); the flare locatlon is correlated wlth the l~mb of the sun. The criter10n: If the solar longitudes are larger than the llmb of the sun. The criterlon: If the solar longitudes are larger than 70°, then they belong to th1s group. The increases asoc~ted w~th these 70°, then they belong to thls group. The increases assoczated wrth these flares can be seen clearly on the onset of the event, above the sta~1flares can be seen clearly on the onset of the event, above the statlstlcal fluctuations. In Fig. 3 we present a superposed epoch analysis centered cal fluctuations. In Fig. 3 we present a superposed epoch analysis centered on the onset of the parent flares w1th coordinate pos~tn on the d~sk on the onset of the parent flares wlth coordinate posltlons on the dlsk 140 140 SH SH 1.4-5 I.4-5 55 MIN MIN -- CHACALTAYA CHACALTAYA NM NM -- DATA DATA .3Z % ++ .3 -- .3 .3 7. -1 -I 9 1I ((hours) hours) I 22 Flg.3. Chree Analysis of 2J vislbles gaIIII or flares (see Table II). Fig.3: Chree _alysis of2Jvis:b;es gamma _ XX-flares (see TableII). The ordInates are of 6-f1oor value. The total length Theo_dmates are gIven gzvenIn ,n Y.Y.of 6-ho_r.an manvalue.Thetotal lengthof of the the plotted data IS three hours. The ORlft of event IS shOlllll .nth plotteddata1$threehours. Theonset of the theeventis shown w:thaa dash. dash. 55 MIN MIN -- CHACALTAYA CHACALTAYA NH Nt_ -- DATA DATA + + .3 X 9 e ------------ _.31 - .3 7. I -1 -I e 8 1 I (hours) (hours) I 2 2 Flg.4, _ree Chree _al_IsofM AnalYSIS of 16 :_isible InvisIble 9_ma_ ga.n or X-flares X- flares (see (Itt TableI). Table I). F19.41 Thi ordinates art given In Y. of 6-f1our .an value. The total length of the the The_dmates_e 9:voninZ of6_onr _ value.Me total lengthof plotted data II t_es thr.. hours. hours. Theon_t Tht onset of of t_ the eventis event IS _om shOlllll .z_ WI th a da_. dash. plotteddatazs when the the sun sun is is above above the the Chacaltaya Chacaltaya horizon. horizon. (( Cf. Cf. Table Table II II). The short short when ). The plotted sample sample illustrates illustrates aa smooth smooth increase, increase, starting starting at at the the onset onset time; time1 plotted no peaks peaks can can be be observed. observed. Among Among these these events events no no dlscrimlnationwas d1scrim1nation was taken taken no into account with the solar zenith angle as seen by Chacaltaya. Finally, into account with the solar zenith angle as seen by Chacaltaya. Finally, F1g. 44 illustrates illustrates the the hlstogram h1stogram of of aa superposed superposed epoch epoch analysls analys1s of of 16 16 solar solar Fig. events with coordinates on the solar d1sk (the1r solar longitudes are less events with coordinates on the solar dlsk (thelr solar longitudes are less than 70°) when the sun is below the Chacaltaya hor1zon and shows a stepthan 70°) when the sun is below the Chacaltaya horlzon and shows a stepl1ke behavlour, behav1our, well well above above the the statistical statistical fluctuatlons,of fluctuat1ons, of the the mean mean vavaIzke lue before before and and after after the the onset onset of of the the events. events. Other Other 'nocturnal'events, 'nocturnal' events, lue not shown shown here, here, do do not not present present any any special special feature feature and and its 1ts analysis analysis shall shall not be be omited. omited. 141141 1. 4-5 SH SH I.4-5 TAIlE TABLE I I TA8lE TABLE II II TAIlE TADI.£ Ill III I I list16lnvzszb]e of 16 Invisible Lzstof Solar Flares tnth Solar SolarFIm'es ruth Solar Longl tudH In the Dill( list 21Vlszble of 21 Vlslble Lzstof Solar Flares .nth Solar SolarFlares.zth Longl tudts In Solar the 01 sIC Lnngztudxzn theDisk list11Visible of 11 Vlslble Lgstof Solar FlINt tilth Solar SolarFlaresruth Solar longltUdts In the lllO Lonoztudes zn theLmb Longztudes zntheDzsk lklset Onset SolarSolarOnset Sol_rSolarOnset SolarSolarOn_tlklset Oat. TIM Coord. Ref Oat. Coord. Tl. Ref Oat. Coord.TzueTl.R_ Ref Date Co_d. Tree Re_ Date Coord, Tree I_ Date Coerd. 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D1scussion 3. Discussion A1thought satellite data is not available 1n order to discriminate solar Althought satellite data is not available in order to discriminate solar sources of neutrons visible from the Chaca1taya neutron monitor, say acsources of neutrons visible from the Chacaltaya neutron monitor, say accord1ng to its 1ntegra1 neutron 1ntensity (wh1ch 1S model dependent), type cordmng to its integral neutron zntensity (whmch zs model dependent), type of photon emiss10n, and the like, we have presented a preliminary superpoof photon emissmon, and the like, we have presented a preliminary superposed epoch analysis of 66 events p1nt-pointed mainly via sate111te flare sed epoch analysis of 66 events pint-pointed mainly via satell_te flare survey. We concentrated on solar events of d1sk or limb parent flares losurvey. We concentrated on solar events of d_sk or limb parent flares location, and when the sun is above or below the Chaca1taya hor1zon. The cation, and when the sun is above or below the Chacaltaya horlzon. The search of solar neutrons V1a neutron mon1tor by other authors and known search of solar neutrons vma nsutron monitor by other authors and known to us (Debruenner et a1., 1983; Iucc1 et a1., 1984) show positive identito us (Debruenner et al., 1983; luccm et al., 1984) show positive identification of solar effects. fication of solar effects. We summar1ze our work: limb flares, when is above or below We summarzze our work: The ~he limb flares, when the the sun sun is above or below the the Chaca1taya hor1zon a) for local nocturnal flares no feature can be noticed Chacaltaya hormzon a) for local nocturnal flares no feature can be noticed and b) for d1urna1 ones the histogram may produce a peak. For parent flaand b) for d_urnal ones the histogram may produce a peak. For parent flalocated on the produce an enhancement of the neutron monitor res res located on the diskdisk theythey produce an enhancement of the neutron monitor intensity before and after the onset times, when the sun is below the Chaintensity before and after the onset times, when the sun is below the Chaca1taya horizon; otherwise no part1cu1ar features be seen. caltaya horizon; otherwise no partmcular features can can be seen. References References Pr1nce et al., 1983, 18th ICRC, Bangalore, ~, 79 Prmnce et al., 1983, 18th ICRC, Bangalore, 4, 79 Debruenner et a1" Chupp et al., 1983, 18th ICRC, Banga10re, 4, 75 Debruenner et al,, Chupp et al., 1983, 18th ICRC, Bangalore, 4, 75 Iucci et a1., 1984, Rome, IFSI-report lucci et al., 1984, Rome, IFSl-report