Time distribution of electromagnetic and hadronic components in giant EAS

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Time distribution of electromagnetic and hadronic

components in giant EAS

J-N. Capdevielle, F. Cohen, A. Aynutdinov, A. Petrukhin

To cite this version:

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Time distributions of electromagnetic and hadronic

components in giant EAS

Jean-No¨el Capdevielle,1 Fabrice Cohen,1 and A. Petrukhin2, V.Aynutdinov2

(1) Laboratoire de Physique Corpusculaire et Cosmologie, Coll`ege de France, 11, Place Marcelin Berthelot , Paris, France

(2) Moscow State Engineering Physics Institute, Moscow

Abstract

From our databank of giant air showers produced by 4D simulation with COR-SIKA, we have derived the time distributions for photons, electrons, muons, charged hadrons and neutrons. Those distributions are compared at diﬀerent distances from the shower core up to 2 km for proton and iron induced cascades.

The average arrival time at diﬀerent distances can help the reconstruction of the axis position and we present some cases of axis determination at 20 m from the actual location in the case of AUGER experiment.

1. Electromagnetic component

Taking the advantage of the 4D-simulation carried with CORSIKA, we have derived the arrival time distributions of the diﬀerent particles in ﬁxed bands of distances, 550 to 650 m, 900 to 1100 m and 1450 to 1750 m.

time gammas at 600m time distr. at 600m, Proton, 0 deg.

0 2500 5000 7500 10000 x 106 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 10126 3977 485.3 270.7 time(ns) all elect. at 600m 0 2000 4000 x 105 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 20126 502 361.1 318.4 time(ns)

time elect.100 MeV at 600m

0 500 1000 1500 2000 x 104 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 22126 168 577.3 614.0 time(ns) time gammas at 1km time distr. at 1000m, Proton , 0 deg.

0 2000 4000 6000 x 105 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 1012 1203 915.2 455.4 time(ns) all elect. at 1km 0 2000 4000 x 104 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 2012 251 835.8 688.3 time(ns)

time elect.100 MeV at 1km

0 1000 2000 3000 4000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 2212 96 821.8 591.6 time(ns) time gammas at 1600m time distr. at 1600m, Proton, 0 deg.

0 2000 4000 x 105 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 101216 566 1571. 826.8 time(ns) all elect. at 1600m 0 1000 2000 3000 4000 x 104 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 201216 149 1374. 770.0 time(ns)

0 1000 2000 3000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 221216 68 1436. 962.5 time(ns)

Fig. 1. time distributions near 600 m, 1000 m and 1600 m from axis, primary proton

1020 eV, for photons, electrons and electrons above 100 MeV (from top)

The average arrival timesτ are listed on Table 1. for the diﬀerent particles and distances. The average situation for proton primary is shown on Fig. 1. and iron primary around the 3 same distances from axis on ﬁg. 2.

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time gammas at 600m time distr. at 600m, Iron, 0 deg.

0 500 1000 x 107 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 10126 4439 480.7 274.4 time(ns) all elect. at 600m 0 2000 4000 6000 x 105 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 20126 656 323.6 238.0 time(ns)

0 1000 2000 3000 x 104 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 22126 235 406.9 400.4 time(ns) time gammas at 1km time distr. at 1000m, Iron , 0 deg.

0 2000 4000 6000 x 105 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 1012 1425 994.1 505.4 time(ns) all elect. at 1km 0 2000 4000 x 104 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 2012 255 788.6 512.5 time(ns)

time elect.100 MeV at 1km

0 1000 2000 3000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 2212 98 831.2 549.4 time(ns) time gammas at 1600m time distr. at 1600m, Iron , 0 deg.

0 2000 4000 x 105 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 101216 730 1481. 710.2 time(ns) all elect. at 1600m 0 1000 2000 3000 4000 x 104 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 201216 192 1476. 971.8 time(ns)

0 1000 2000 3000 4000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 221216 64 1167. 831.0 time(ns)

Fig. 2. time distributions near 600 m, 1000 m and 1600 m from axis, primary iron

1020 eV, for photons, electrons and electrons above 100 MeV (from top)

2. Muons, hadrons and neutrons

A general leptonic synchronism is observed with comparable mean arrival times for electrons and muons (larger than 25-30% for photons).

time muons at 600m time distr. at 600m, Proton, 0 deg.

0 2000 4000 x 104 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 50126 5821 359.4 353.2 time(ns) time hadrons at 600m 0 2000 4000 6000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 80126 196 1442. 706.2 time(ns) time neutrons at 600m 0 2000 4000 6000 8000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 86126 224 2269. 1132. time(ns) time muons at 1km time distr. at 1000m, Proton, 0 deg.

0 500 1000 1500 2000 x 104 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 5012 3215 717.1 568.3 time(ns) time hadrons at 1km 0 2500 5000 7500 10000 x 102 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 8012 105 2178. 835.9 time(ns) time neutrons at 1km 0 1000 2000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 8612 181 3137. 1247. time(ns) time muons at 1600m time distr. at 1600m, Proton, 0 deg.

0 2000 4000 6000 8000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 501216 2302 1238. 986.5 time(ns) time hadrons at 1600m 0 1000 2000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 801216 78 3139. 859.2 time(ns) time neutrons at 1600m 0 1000 2000 3000 4000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 861216 164 5022. 1852. time(ns)

Fig. 3. time distributions near 600 m, 1000 m and 1600 m from axis, primary proton

1020 eV, respectively for muons, hadrons and neutrons above 300 MeV (from the

top) .

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time muons at 600m time distr. at 600m, Iron, 0 deg.

0 2000 4000 6000 8000 x 104 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 50126 8079 353.0 362.5 time(ns) time hadrons at 600m 0 2000 4000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 80126 228 1394. 554.5 time(ns) time neutrons at 600m 0 2000 4000 6000 8000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 86126 327 2166. 1015. time(ns) time muons at 1km time distr. at 1000m, Iron, 0 deg.

0 1000 2000 3000 x 104 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 5012 4544 744.1 645.2 time(ns) time hadrons at 1km 0 5000 10000 x 102 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 8012 130 2146. 792.0 time(ns) time neutrons at 1km 0 1000 2000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 8612 222 3454. 1481. time(ns) time muons at 1600m time distr. at 1600m, Iron, 0 deg.

0 500 1000 1500 x 104 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 501216 3395 1216. 893.4 time(ns) time hadrons at 1600m 0 1000 2000 3000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 801216 103 3462. 1412. time(ns) time neutrons at 1600m 0 2000 4000 x 103 0 2000 4000 6000 8000 10000 ID Entries Mean RMS 861216 202 4496. 1421. time(ns)

Fig. 4. time distributions near 600, 1000 m, and 1600 m from axis, primary Iron

1020 eV, respectively muons, hadrons and neutrons above 300 MeV (from the top)

.

Table 1. Average arrival times (in ns) for the diﬀerent particles at 600, 1000 and 1500 m from axis. τγ τe τµ τh τn σγ σe σµ σh σn r=600 m, prim.p 483 361 359 1440 2270 483 361 359 1440 2270 r=600 m, prim. Fe 480 323 353 1394 2166 275 238 362 554 1015 r=1000 m, prim.p 915 821 717 2178 3137 455 688 568 836 1247 r=1000 m, prim. Fe 992 788 744 2146 3454 505 512 645 792 1481 r=1600 m, prim.p 1571 1374 1238 3139 5022 826 770 986 859 1852 r=1600 m, prim. Fe 1480 1476 1216 3462 4496 710 971 893 1412 1421

3. Time structure of the shower front

Average time of arrival component at diﬀerent distances compared with Linley dispersion at diﬀerent distances.

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542

neutrino interaction.

According to the probabilities in regard of the low densities of hadrons and neutrons to pass simultaneously out of the field of the different tanks, or to cross without visible effect, it can be roughly estimated that 20% proton showers can have a signature by delayed hadronic signal.

The thickness of the electron shower front σ(r) (Fig. 5.) increases with distance according to

σ(r) = 2.6(1 + r

25.)

1.4 ₍₁₎

as derived from our simulation with CORSIKA for near vertical showers. Those values, up to 2000 m, are in agreement with the adaptation of Linsleys’s previous estimation [4] adapted for AGASA [7]. The original experimental mea-surements values are closed from the simulation Fig. 5.

flns

Average shower front thickness (ns)

0 200 400 600 800 1000 1200 0 200400600800 1000 1200 1400 1600 1800 2000 R(m) τ (ns) avtime

Average time delay for electrons from simulation

0 100 200 300 400 500 0 200 400 600 800 1000 1200 R(m) τ (ns) ∆R Core

Dist. between core fitted - true core of shower

0 2 4 6 8 10 12 14 16 18 0 10 20 30 40 50 60 70 80 ID Entries Mean RMS 1 121 27.18 18.39 R(m)

Fig. 5. Left: Average shower front thickness (ns). Our simulation with CORSIKA

(solid line) is compared to the experimental data of Akeno exended to 20 km2 [5]

and Akeno [3] (average from 10 EAS). Primary particle is a proton with energy

1011 GeV. The adaptation of Linsley’s prediction to AGASA (dahed line)

corre-sponds to showers up to zenith angle of 40o . Middle: Average time delay for

electrons from our simulation (solid line) compared to the data of [6] (dashed) . Right: Core reconstruced using time delay, error on the core: near 30 m

This work has been supported by INTAS 99-1339. 4. References

1. Borisov A. 2001, Proc. ECRS, Geneve in the press 2. Capdevielle J.N. 1988, J. Phys. G, 14, 503

3. Kakimoto F. 1985, Proc. 19th ICRC (La Jolla) 7,328 4. Linsley J. 1986, J. Phys. G, 12, 51

5. Teshima M. 1986, J. Phys. G, 12, 1097-1113