Eiji Kamioka

Composition and energy spectra of cosmic ray primaries in the energy range 1013 - 1015 eV/particle observed by Japanese-Russian joint balloon experiment

Abstract We report experimental results obtained by the emulsion chambers on board of the long duration balloon. We have been carrying out the trans-Siberian-continental balloon flight since 1995, and the results from 1995 to 1996 experiments are presented here. Total exposure of these two years amounts to 231.5 m 2 h at the average altitude of ∼32 km. The energy range covers 10–500 TeV for proton-primary, 3–70 TeV/n for helium-primary, and 1–5 TeV/n for Fe-group ( Z =26–28), though statistics of heavy components is not yet enough. Our preliminary data show that the spectra of the proton and the helium have nearly the same power indices ∼2.80, while those of heavier ones become gradually harder as the mass gets heavier, for instance the index is ∼2.70 for CNO-group and ∼2.55 for Fe-group. It is remarkable that a very high energy proton with multi-PeV is detected in 1995 experiment, and the estimated flux of this event coincides with a simple extrapolation from the energy spectrum with the power index 2.8 observed in the range 10–500 TeV. It indicates that there is no spectral break at around 100 TeV, in contrast to the maximum energy predicted by the current shock-wave acceleration model. This evidence requires some modification on the acceleration and/or propagation mechanism. Also we present all-particle spectrum and the average primary mass in the energy range 20–1000 TeV/particle. Our preliminary data show no drastic change in mass composition over the wide energy range, at least up to 1 PeV/particle, though the statistics is not yet enough to confirm it concretely. The flight performance and the procedure of the analysis, particularly the energy determination methods and the detection efficiency calculation are also given.

Cosmic-Ray Spectra and Composition in the Energy Range of 10-1000 TeV per Particle Obtained by the RUNJOB Experiment

This is a full report on the cosmic-ray spectra and composition obtained by the emulsion chambers on board 10 long-duration balloons, launched from Kamchatka between 1995 and 1999. The total exposure of these campaigns amounts to 575 m2 hr, with an average flight altitude of ~32 km. We present final results on the energy spectra of two light elements, protons and helium nuclei, and on those of three heavy-element groups, CNO, NeMgSi, and Fe, covering the very high energy region of 10-1000 TeV particle-1. We additionally present the secondary/primary ratio, the all-particle spectrum, and the average mass of the primary cosmic rays. We find that our proton spectrum is in good agreement with other results, but the intensity of the helium component is nearly half that obtained by JACEE and SOKOL. The slopes of the spectra of these two elements obtained from RUNJOB data are almost parallel, with values of 2.7-2.8 in the energy range of 10-500 TeV nucleon-1. RUNJOB heavy-component spectra are in agreement with the extrapolation from those at lower energies obtained by CRN (Chicago group), monotonically decreasing with energy. We have also observed secondary components, such as the LiBeB group and the sub-Fe group, and present the secondary/primary ratio in the TeV nucleon-1 region. We determine the all-particle spectrum and the average mass of the primary cosmic rays in the energy region of 20-1000 TeV particle-1. The intensity of the RUNJOB all-particle spectrum is 40%-50% less than those obtained by JACEE and SOKOL, and the RUNJOB average mass remains almost constant up to ~1 PeV.

Access Control for Security and Privacy in Ubiquitous Computing Environments

Ubiquitous computing (ubicomp) demands new security and privacy enhancing technologies for the new information and communication environments where a huge number of computers interact with each other in a distributed and ad hoc manner to access various resources and services. This paper surveys emerging security and privacy enhancing technologies, focusing on access control in ubiquitous computing environments because this is the underlying core technology to enforce security and privacy policies. We classify access control technologies into three types associated with the three access control phases of prevention, avoidance, and detection, and provide an overview of ubiquitous computing-oriented technologies and solutions, ranging from security and privacy models and policies to the enforcement of policies and system implementation.

Unusually penetrating particle detected by balloon-borne emulsion chamber

SummaryOne example of an unusual particle track has been recorded in an emulsion chamber exposed to cosmic rays on a ballon at the atmospheric depth 11.7 g/cm2. The particle arrived at the chamber withZ/β=40±2 and β≳0.8. What is extraordinary with this particle is its arrival zenith angle, 87.4°, which amounts to a traversed atmospheric thickness ∼200 g/cm2. The anomalous nature of the present track “ET” (exotic track) is demonstrated through the difficulties in reconciling it with the explanation that it is due to an ordinary ultra-heavy cosmic-ray nucleus.

An Anonymous Context Aware Access Control Architecture For Ubiquitous Services

A new context aware access control architecture called Anonymous Context Aware Access Control Architecture (ACA2) is proposed. The basic idea of this architecture is based on an analogy to the public telephone service. Anonymous users can use services supported by their context information through preregistered software components called proxies. The main features of the architecture include anonymity, access suspension caused by context changes, and active context certificates with stream verification.

Maximizing user satisfaction based on mobility in heterogeneous mobile multimedia communication networks

Future wireless/mobile system is expected to have heterogeneous wireless overlay networks for ubiquitous multimedia communication. In a such network environment, mobile users are likely to try to get attached to higher bandwidth network as bandwidth-hungry multimedia applications are increasing. However, the users have to perform vertical handoff to lower bandwidth network, as high bandwidth network become unavailable due to various reasons (such as its limited coverage, network congestion, etc.). In this paper, we discuss the problem of vertical handoff from a users perspective. For this purpose, we formulate user satisfaction as a function of bandwidth utility and handoff latency. Then, we investigate the effect of call holding time, user movement probability, etc. on the satisfaction that a user derives from the use of network service for multimedia applications. In addition, based on the evaluation, we present an algorithm for selecting a wireless network, which maximizes the effective user satisfaction.

MoRaRo: Mobile Router-Assisted Route Optimization for Network Mobility (NEMO) Support

The IETF (Internet Engineering Task Force) has developed a Network Mobility (NEMO) basic support protocol by extending the operation of Mobile IPv6 to provide uninterrupted Internet connectivity to the communicating nodes of mobile networks. The protocol uses a mobile router (MR) in the mobile network to perform prefix scope binding updates with its home agent (HA) to establish a bi-directional tunnel between the HA and MR. This solution reduces location-update signaling by making network movements transparent to the mobile nodes behind the MR. However, delays in data delivery and higher overheads are likely to occur because of sub-optimal routing and multiple encapsulation of data packets. To resolve these problems, we propose a mobile router-assisted route optimization (MoRaRo) scheme for NEMO support. With MoRaRo, a mobile node performs route optimization with a correspondent node only once, at the beginning of a session. After that the MR performs route optimization on behalf of all active mobile nodes when the network moves. The virtue of this scheme is that it requires only slight modification of the implementation of the NEMO basic support protocol at local entities such as the MR and mobile nodes of the mobile network, leaving entities in the core or in other administrative domains untouched. MoRaRo enables a correspondent node to forward packets directly to the mobile network without any tunneling, thus reducing packet delay and encapsulation overheads in the core network. To enable the scheme to be evaluated, we present the results of both theoretical analysis and simulation.

Azimuthally controlled observation of heavy cosmic-ray primaries by means of the balloon-borne emulsion chamber

Abstract We have exposed an emulsion chamber with an area of 1.22 m 2 on board of the balloon at an atmospheric depth of 8.9 g/cm 2 for 15.8 h, which has been azimuthally controlled within the accuracy of Δφ = 0.5°. With the use of the east-west asymmetry effect of arriving cosmic-ray primaries, we can obtain the energy spectra for individual elements in the kinetic energy range from a few GeV/nucleon up to ∼ 15 GeV/nucleon. We present also the energy spectra obtained by the opening-angle method for the higher energy region, 5–1000 GeV/nucleon, for the elements not lighter than silicon. We find that the energy spectra obtained by the former method continue smoothly to those obtained by the latter, indicating that the energy determination using the opening-angle method is performed correctly. We compare also the present results with those obtained by the previous work. We find that the iron flux is in nice agreement with that obtained by the previous observation, the differential spectral index being constant, ∼ 2.5, up to a few TeV/nucleon, while in the case of the silicon component, it is ∼ 2.7 for 10–1000 GeV/nucleon in this work, significantly harder than the previous one, ∼ 2.9. We also report the flux of the sub-iron component and its abundance ratio to the iron component. We find the abundance ratio of [Z = 21–25]/iron is slightly less than those obtained previously in the higher energy region, ≳ 100 GeV/n.

Extended Correspondent Registration Scheme for Reducing Handover Delay in Mobile IPv6

We present a new scheme for fast binding update with correspondent nodes to expedite the handover operation of mobile nodes in Mobile IPv6 protocol supporting networks. Our scheme is an extension of the Mobile IPv6 correspondent registration process that modifies some messages exchanged between a mobile node and a correspondent node. This scheme reduces the handover latency while providing the same level of security assurances for revealing the location information to the correspondent node as in the current Mobile IPv6 protocol. We also present an extension of the scheme to multihomed mobile nodes that have heterogeneous interfaces.

CoMoRoHo: Cooperative Mobile Router-Based Handover Scheme for Long-Vehicular Multihomed Networks

To support multimedia applications effectively in mobile networks, the handover latency or packet losses during handover should be very small. Addressing this issue, we present a cooperative mobile router-based handover (CoMoRoHo) scheme for long-vehicular multihomed mobile networks. The basic idea behind CoMoRoHo is to enable different mobile routers to access different subnets during a handover and cooperatively receive packets destined for each other. In general, packet losses are directly proportional to handover latency; however, the overlapped reception of packets from different subnets makes possible to minimize packet losses even without reducing handover latency. To evaluate the scheme, we carried out performance modeling of the CoMoRoHo scheme in comparison with the Fast Handover for Mobile IPv6 (FMIPv6) protocol in regard to the handover latency, packet loss, signaling overhead, and packet delivery overhead in access networks. The analysis results show that CoMoRoHo outperforms FMIPv6 by reducing the packet losses as well as signaling overheads by more than 50%. Moreover, CoMoRoHo imposes lower packet delivery overheads required for preventing packets from being dropped from access routers. We thus conclude that CoMoRoHo is a scalable scheme because its performance remains intact even when the access network is overloaded.