Preparation of Manuscripts for RT2001

1 NSCLSpecTcl Meeting the Needs of Preliminary Nuclear Physics Data Analysis Ron Fox, Chase Bolen, Kanayo Orji, Jason Venema • Section V will describe the structure of the Abstract--The National Superconducting Cyclotron Laboratory NSCLSpecTcl C++ application framework, introducing at Michigan State University (NSCL) is a user facility performing the technology of application frameworks, the structure basic reasearch in heavy ion collisions with rare isotopes. A wide of the framework we have developed, describing how variety of experiments are performed at the NSCL, each with Tcl/Tk is integrated into the software as a control specialized analysis needs. Providing a package that balances ad- hoc extensibility and performance was the distinct challenge language. facing the NSCL software support staff. We chose to implement a • Section VI will describe some of the extensions that hybrid C/C++ application framework and TCL/Tk extension have been written for NSCLSpecTcl. language. This paper will describe nuclear experimental physics, • The paper will conclude with a summary of the the needs of the community, how they are met by NSCSLSpecTcl, experiences with the system, the level of community the structure of the software and the extension language. We will also describe several extensions to NSCLSpecTcl that have been acceptance within the NSCL and the nuclear physics created by the user community and others. community in general. The availability of the software will be described as well. I. INTRODUCTION II. BACKGROUND HIS paper will describe a Tcl/Tk[1] extension that In this section we will describe how experimental nuclear Tconsists of a C++ application framework that is physicists study the structure of the atomic nucleus. The controlled by an extended Tcl/Tk interpreter. NSCLSpecTcl National Superconducting Cyclotron Laboratory (NSCL), a is intended to be used during online and early stage offline National Science Foundation (NSF)[3] funded university analysis of nuclear physics event data. The structure of the laboratory will be introduced and its research agenda will be paper will be as follows: placed in the context of national near-term and long-range • Section II will introduce experimental nuclear physics, nuclear science research goals. the National Superconducting Cyclotron Laboratory A. Experimental Nuclear Physics (NSCL) [2] and its research objectives. Research at the NSCL will be placed in the context of the national goals In experimental nuclear physics, scientists study the structure of the core of the atom through particle-nucleus collisions. By for basic research. scattering particles off the nucleus we can learn about the inner • Section III describes the requirements of the software. composition, shape of the nucleus as well as improve our We will describe technical as well as usability goals. understanding of the forces that govern nucleon-nucleon • Section IV describes the approach of other packages in interactions. use in nuclear and high energy physics that embed scripting languages provides the motivation for our Particles are scattered off the nucleus either in collider or choice of Tcl/Tk as an embedded scripting language for fixed target accelerator systems. In a collider two accelerated NSCLSpecTcl. beams of nuclei move in opposite directions. The two beams intersect, causing some of the nuclei in one beam to collide with particles in the other beam. In fixed target systems, a particle accelerator accelerates a beam of projectiles that is Ron Fox is with the National Superconducting Cyclotron Laboratory at transported to a target consisting of the element being studied. Michigan State University, East Lansing, MI 48824-1321 In either case, complex detector systems surround the Chase Bolen is currently a graduate student in the Department of Electrical Engineering at Michigan State University, East Lansing, MI 48824 interaction region to capture and measure the properties of the Kanayo Orji is now a Medical Student at the Medical School of Wayne resulting collision fragments. While higher reaction energies State University, Detroit Michigan are possible with collider systems, these systems are generally Jason Venema is an employee of Boeing Corp St. Louis MO 63166 2 limited to the study of symmetric systems. Fixed target The cyclotrons are capable of accelerating beams as heavy as systems, on the other hand support the study of asymmetric Uranium with energies of up to about 1GeV/nucleon. An systems. electron volt (eV) is the energy gained by an electron falling through a potential energy difference of 1V. The electrons Electrons and other nuclei have been used as projectiles in returning to your car battery have an energy of about 12eV. fixed target systems. Electrons, are not subject to the nucleon- At the other end of the energy scale, a typical donut has the nucleon force, but will scatter off the charge of the protons in chemical energy equivalent of 1015 GeV. the nucleus, and therefore make excellent probes of the spatial structure of the nucleus. Using nuclei as projectiles A unique feature of the NSCL is the A1900 fragment provides information about the interactions of the constituents separator. Primary beam from the cyclotrons interacts with a of the nucleus with each other. This allows scientists to probe production target at the entrance of the A1900. Fragments of the energy level scheme of the nucleus, the stability of the the projectile enter a spectrograph where the isotopes of nucleus under deformation and, if sufficient numbers of interest are selected. These projectile fragments continue to nucleons interact, the statistical properties of nuclear matter. travel with energies close to those of the primary beam. This allows exotic nuclei to be transported to experimental targets. Figure 1 shows a schematic of an event in typical fixed The A1900 allows researchers at the NSCL to study the target experiment. An event is a single collision that properties of highly unstable isotopes that do not occur in produces measurable results. Figure 1 shows the remnant of nature. Figure 2 and 3 show NSCL experimental area floor a projectile that has scattered at some angle to its original plan as well as as schematic of the A1900. incident trajectory, a target remnant knocked out of the target fragments scattered target detector system Figure 2 The NSCL experimental floor plan. scattered projectile in the forward direction and a scattering of smaller fragments that may have come from the projectile, the target or both. A detection system around the target area will capture and detect the properties of some or all of these reaction products. Figure 1 Schematic view of nucleus-nucleus collisions in a fixed target system. Figure 3 The A1900 mass separator B. The National Superconducting Cyclotron Laboratory The NSCL is a user facility. Scientists from all over the world submit proposals to an independent Program Advisory The National Superconducting Cyclotron Laboratory at Committee which awards beam time on the basis of scientific Michigan State University (NSCL) is a National Science merit. Foundation supported university laboratory that performs nuclear physics experiments. The NSCL has a pair of cyclotrons that accelerate beams for fixed target experiments. 3 C. The NSCL and U.S. scientific research goals. NSCL research is focused on interactions between heavy ions. Heavy ion physics research helps us understand the nature of the inter-nucleon strong force, and to probe the statistical properties of nuclear matter such as the nuclear equation of state and phase transitions that may occur in hot nuclear matter. Experiments with unstable isotopes from the A1900 allow us to answer questions about the properties of nuclear matter in conditions far from stability. This has direct bearing on understanding what happened in the early universe and what happens in the interiors of stars. Measuring the lifetimes, decay modes and the probabilities of each decay mode (branching ratios) contribute to an understanding of the distribution of isotopes in the universe and how this distribution came about. Figure 4: The Rare Isotope Accelerator (RIA) at MSU. In the past several years the U.S. nuclear physics community has been moving towards the development of a new raw event data acquired from the digitizers attached to the experimental facility called the Rare Isotope Accelerator detector system must be decoded to produce a set of (RIA). The NSCL A1900 is the precursor facility to RIA. parameters. These parameters may be as simple as the height When built, RIA will extend the energies and intensities of the of a voltage pulse from a solid state detector that stops a heavy beams of exotic nuclei that can be produced enabling fragment, or as complex as computing fragment positions vi a experiments with nuclei even further away from stability. In Gaussian fit to the charge deposited on a set of pads in a 2002, RIA was endorsed by the DOE/NSF Nuclear Science Cathode Readout Drift Chamber . Advisory committee as the one of the second highest priorities for funding [4]. In November 2003, U.S. Energy Secretary Experimenters need to: Spencer Abraham released the Office of Science priority list • Histogram individual detector channels to monitor their showing funding for RIA tied for third place amongst the near- health. Histograms can be of several types including term priorities [5]. NSCL accelerator physicists have been a simple single parameter histograms, histograms of leaders in the conceptual design of the RIA facility. MSU is parameter pairs (2-d), histograms of the bits set in a competing with Argonne National Laboratory to host RIA. bitmask, histograms showing summaries of the data in Since the NSCL is a world leader in the production of rare multiple similar channels (summary Spectra) or isotope beams by projectile fragmentation, MSU would be the histograms that are multiply incremented for several logical place to build RIA. parameters (e.g γ-ray decay cascade histograms). • Calculate and histogram calibrated parameters by An architectural sketch of the ½ km long linear accelerator that transforming raw parameters to physically meaningful will make up RIA is shown in Figure 4 below.

Load more