1. Beam Energy Measurements with Elastic Scattering At Jefferson Lab an electron beam is used to probe the nucleus. In these experiments it is essential to know the precise energy of the beam. At Jefferson Lab an electron beam is used to probe the nucleus. In these experiments it is essential to know the precise energy of the beam. To measure the energy, Jefferson Lab uses a device that measures the angles of an elastic collision. To measure the energy, Jefferson Lab uses a device that measures the angles of an elastic collision. By: Idaykis Rodriguez Florida International University, Miami, Fl 33199 Mentor: Douglas W. Higinbotham e p Electron beam Scattered electron Scattered proton target The target in the device is a polymer film rich in hydrogen, ie. rich in protons. The film is made of polypropylene (C 3 H 6 ) material which runs constantly on the rollers controlled by a motor. This is done to prevent the electron beam from melting the target. As the electron beam travels through the target, it looses some energy that turns into heat. The energy loss correction can be calculated using the Bethe-Bloch equation. As the electron beam travels through the target, it looses some energy that turns into heat. The energy loss correction can be calculated using the Bethe-Bloch equation. eP DEVICE INTRODUCTIONINTRODUCTION The eP device measures a fixed proton angle at 60 0 and simultaneously measures the electron from the elastic collision. The eP device measures a fixed proton angle at 60 0 and simultaneously measures the electron from the elastic collision. Detectors within the eP device include scintillators, Cherenkov detectors, and silicon strips detectors. Detectors within the eP device include scintillators, Cherenkov detectors, and silicon strips detectors. In order to have the eP device operational again, many updates and mechanical parts need to be replaced. In order to have the eP device operational again, many updates and mechanical parts need to be replaced. Updates to the systems data analysis program needed to be made. With the help of CODA experts, we were able to identify glitches and bugs that needed repair. Updates to the systems data analysis program needed to be made. With the help of CODA experts, we were able to identify glitches and bugs that needed repair. Bearings for the rollers of the target film were replaced. We determined that the ceramic ball on steel races bearing does not perform well under a vacuum environment. We found a ceramic ball on ceramic races bearing which perform very well in vacuum. Bearings for the rollers of the target film were replaced. We determined that the ceramic ball on steel races bearing does not perform well under a vacuum environment. We found a ceramic ball on ceramic races bearing which perform very well in vacuum. This is the eP device along the beamline. These are the Cherenkov light detectors and close to the octagon, are the scintillators and photomultiplier tubes which detect charged particles. TARGETSTARGETS ACKNOWLEDGEMENTSACKNOWLEDGEMENTS Special thanks are given to: Douglas W. Higinbotham Douglas W. Higinbotham Jan Tyler Jan Tyler Ed Folts Ed Folts Marcy Stutzman Marcy Stutzman David Meekins David Meekins Alexandre Camsonne Alexandre Camsonne Robert Michaels Robert Michaels Pierre Bertin Phil Atterly Phil Atterly Lisa Surles-Law Lisa Surles-Law David Abbott (both) David Abbott (both). These are samples of a full ceramic bearing. 12 GeV UPGRADE The figure on the left shows the energy acceptance of eP device for the current location of the silicon strips. The green and orange indicate silicon strips proposed to move to an angle of 5 0 for the new 11GeV desired energy in the red and the other silicon strip to move to an angle of 49.2 0 for detecting protons, which refers to the figure on the right. The desired energies for the 12 GeV upgrade are 2.2, 4.4, 6.6, 8.8, and 11 GeV. We propose to move four silicon strips to new locations to detect the whole range of desired energies. Inside the octagon piece are the silicon strips at their specific angles and the entire device is symmetric about the beamline. 1 C 3 H 6 is the current target in eP, chosen for its high hydrogen ratio but it quickly melts in the beam due to its low thermal conductivity. 2 H 2 O is a flowing target with a large energy loss (creates heat) due to its thickness. 3 Kapton was considered because of its high melting point but, its hydrogen ratio is very poor. 4 CVD Diamond foil was considered as a backing material to the current polymer for its high thermal conductivity, but it could be too thick for the eP device. 5 Carbon Nanotubes alone have the best thermal conductivity. A composite mixture with 90% polypropylene and 10% carbon nanotubes could be an ideal target. The energy of the beam is then calculated using the following equation: The energy of the beam is then calculated using the following equation: