Wednesday, May 19, 2010

arkansas 229.ark.00 Louis J. Sheehan, Esquire

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Hillary left Washington and followed her heart to Arkansas, marrying Bill Clinton in 1975. The couple taught together on the law faculty of the University of Arkansas at Fayetteville. Their daughter, Chelsea, was born in 1980.

As First Lady of Arkansas, Hillary continued to work tirelessly on behalf of children and families. In addition to chairing the Arkansas Education Standards Committee, she founded the Arkansas Advocates for Children and Families. She introduced a pioneering program called Arkansas Home Instruction for Preschool Youth, which trained parents to work with their children in preschool preparedness and literacy. Hillary also served on the board of the Arkansas Children's Hospital. In recognition of her professional and personal accomplishments, Hillary was named Arkansas Woman of the Year in 1983 and Arkansas Mother of the Year in 1984.

Like her predecessors, Hillary Rodham Clinton brings to the role of First Lady of the United States her own special talents, experience, style, and interests. The President appointed her to head his Task Force on national Health Care Reform, one of his highest priorities on taking office.

Women's International Center proudly presents the Living Legacy Award to Hillary Rodham Clinton for her vast contributions in so many fields, especially honoring her work for women and children.

Monday, May 10, 2010

paratroopers 883.par.003 Louis J. Sheehan, Esquire

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The paratroopers were involved in very heavy fighting at night. They attacked, and they suffered great losses; we sent tanks to help them. And in the morning, I had two brigades fighting tanks from the north. We managed to evacuate the paratroopers, who had a great deal of losses. And on the other side, from afar we saw the brigade advancing from the south. I asked for another brigade of mine that was being held in reserve, and I received it; it was being held at the command. It advanced from afar; it had to move for about four hours. In the meantime, the Egyptians were advancing from the south, and at the same time we were lying underneath camouflage nets and the equipment, while the paratroopers fought at night, and we saw that they were not able to clear the entire area. I decided to take a calculated risk and, under cover of their fighting, I pushed all my crossing equipment, the rafts, to Sharon, and from six in the morning they began to make bridges over the tanks, under artillery fire. While he was building these bridges, andI was...

Sunday, May 2, 2010

neutrino 448.neu.773 Louis J. Sheehan, Esquire

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Electrons and Positrons

The electron has a mass of 0.000511 GeV/c2. The electron is the least massive charged particle of any type. It is absolutely stable because conservation of energy and electric charge together forbid any decay.

The antiparticle of the electron is called a positron. It has exactly the same mass as the electron, but the opposite sign (+1) for its electric charge. Positrons are also stable particles. However, positrons can annihilate when they meet an electron. Both the electron and the positron vanish, and their energy goes into photons and, possibly, more massive particles. Conversely, photons with sufficient energy (E > 2x (mass of electron) x c2) can produce an electron and a positron -- this is called pair production.
Muons (Greek letter for Muon)

The muon has a mass of 0.106 GeV/c2. The negatively charged muon (mu-minus) is just like an electron, except it is more massive. Muons are unstable -- they decay to produce a virtual W-boson and the matching neutrino type. The W-boson then decays to produce an electron and an electron-type anti-neutrino.

The antiparticle of a mu-minus is a mu-plus. Particle physicists use the name muon for either mu-plus or a mu-minus a muon. The mu-plus decays to produce an anti-muon type neutrino and a W-plus boson, which then decays to a positron and an electron-type neutrino.

Muons are produced in particle physics experiments. They also are produced by cosmic rays. Because they are much more massive than electrons, muons readily pass through the electric fields inside matter with very little deflection. So, muons do not radiate and slow down as electrons do. However, they can cause ionization and this makes them readily detectable in matter, for example, with a Geiger counter.
Tau Leptons (Tau Lepton symbol)

The tau-minus is a electron-like particle with a mass of 1.784 GeV/c2. Its antiparticle, the tau-plus, has the same mass but a positive electric charge. These particles were discovered at SLAC in experiments at SPEAR. The 1995 Nobel Prize was awarded for this discovery.

This third type of charged lepton is also unstable. The tau-minus decays to produce its matching neutrino and a virtual W-minus boson. The W-minus has enough energy that there are several possible ways for it to decay, such as:

1. An electron and an electron-type antineutrino.
2. A um-minus and an muon- type antineutrino.
3. A down quark and an up-type antiquark.
4. An s quark and an up-type antiquark.

The quark and antiquark do not emerge individually. One or more mesons emerge from the decay that contain the initial quark and antiquark, and possible additional quark-antiquark pairs produced from the energy in the strong force field between them.

For tau-plus, a similar set of decays occurs -- just replace every particle by its antiparticle (and vice-versa, every antiparticle by the matching particle.) Thus, for example, tau-plus can decay to give a tau type anti-neutrino and a positron and an electron-type neutrino.
Neutrinos (Electron Neutrino, Muon Neutrino,Tau Neutrino)

There are three types of neutrinos, one associated with each type of charged lepton. All are particles that are somewhat like electrons: they have half a quantum unit of spin angular momentum, and do not participate in strong interactions.

However, neutrinos differ from electrons in that they have zero electric charge and, as far as we know today, zero mass. Experimentally, all we can do is set an upper limit on their masses -- they are smaller than some value. Larger masses would have had observable effects in some experiment. The limits are:

* electron neutrino less than 0.00000002 GeV/c2 for electron type neutrinos (or antineutrinos).
* muon neutrino less than 0.0003 GeV/c2for muon type neutrinos (or antineutrinos).
* tau neutrino less than 0.04 GeV/c2for tau type neutrinos (or antineutrinos).

The only known difference between the three neutrino types is which type of the charged lepton they are associated with during production or decay processes.

Since neutrinos have no electric charge, they participate only in weak interaction or gravitational processes. For this reason, they are very difficult to detect. We observe them only by the effects they have on other particles with which they interact.

For example, a high-energy electron-type neutrino can convert to an electron by exchanging a W-boson with a neutron (which becomes a proton when it absorbs the W boson). This rarely happens. With an intense source of neutrinos and a large detector containing many neutrons, one can observe events with no visible initiating particles that can only be explained as neutrino-initiated processes. What is seen in the detector is the recoiling electron and proton after the process occurs. (Experimental work demonstrating this process resulted in Frederick Reines sharing the 1995 Nobel Prize with Martin Perl.)

Even harder to see is the process where the neutrino is deflected by exchanging a Z-boson with a proton or neutron. The proton or neutron gains energy from this exchange, so one searches for events where a recoiling proton or neutron is seen with no associated electron and no visible initiating particle.

In high-energy particle experiments, we often use energy and momentum conservation to infer that production of one or more neutrinos occurred. If the detector detects everything but neutrinos, then an event where the total final energy detected (or the total final momentum) does not match the initial energy (or momentum) in the incoming particles, then neutrinos must have been produced. The neutrinos carried off the missing energy (and momentum).