# Presentation: 657651

## BES Operates Four Major Research Facilities for Neutron Scattering

***The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory***
***The Manuel Lujan, Jr. short pulse spallation source at the Los Alamos Neutron Science Center (LANSCE) at Los Alamos National Laboratory***
***The High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory***
***The High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory***

***Experimental Floor******High Flux Beam Reactor (BNL)***

***Powder Diffractometer******High Flux Isotope Reactor (ORNL)***

***PHAROS******LANSCE (LANL)***

***Powder******Diffractometer******Intense Pulsed******Neutron Source******(ANL)***

## U.S. Advisory Groups Recommending Neutron Sources

**1984****	**** --****	****National Research Council report *****Major Facilities for Materials ******	******	******	******Research and Related Disciplines***** (The Seitz-Eastman Report)**
**1985****	**** --****	****Energy Research Advisory Board Materials ad Hoc Panel**
**1987****	**** --****	****National Research Council Physics Review Panel**
**1987****	**** --****	****Energy Research Advisory Board Physics Review Panel**
**1987****	**** --****	****Basic Energy Sciences Advisory Committee**
**1988****	**** --****	****Basic Energy Sciences Advisory Committee**
**1989****	**** --****	****National Research Council Materials Science and Engineering ****	****	****	****Committee**
**1990****	**** --****	****Basic Energy Sciences Advisory Committee**
**1992****	**** --****	****Basic Energy Sciences Advisory Committee Panel report*****	******	******Neutrons for America's Future *****(The Kohn Report)**
**1996****	**** --****	****Basic Energy Sciences Advisory Committee Panel on the****	****	****Next-Generation Spallation Source  (The Russell Report)**

## A Few of the Advisory & Community GroupsAddressing X-ray and Neutron Sources

**1984****	**** --****	****National Research Council report *****Major Facilities for Materials Research and Related Disciplines*****	****	****(The Seitz-Eastman Report)**
**1985****	**** --****	****Energy Research Advisory Board Materials ad Hoc Panel**
**1987****	**** --****	****National Research Council Physics Review Panel**
**1987****	**** --****	****Energy Research Advisory Board Physics Review Panel**
**1987****	**** --****	****Basic Energy Sciences Advisory Committee**
**1988****	**** --****	****Basic Energy Sciences Advisory Committee**
**1989****	**** --****	****National Research Council Materials Science and Engineering Committee**
**1990****	**** --****	****Basic Energy Sciences Advisory Committee**
**1992****	**** --****	****Basic Energy Sciences Advisory Committee Panel report *****Neutrons forAmerica's Future******	******	*****(The Kohn Report)**
**1996****	**** --****	****Basic Energy Sciences Advisory Committee Panel report on Upgrades to Reactor and****	****	****Spallation Neutron Sources and the Technical Specificiations of the Next-Generation****	****	****Spallation Source  (The Birgeneau, Aeppli, and Russell Reports)**
**1997 ****	**** -- ****	****Basic Energy Sciences Advisory Committee Panel report *****Synchrotron Radiation Sources******	******	******and Science***** (The Birgeneau Report)**
**1997 ****	**** -- ****	****BioSync Report *****Structural Biology nad Synchrotron Radiation: Evaluation of Resources******	******	******and Needs***

## Seminal Studies of Major Facilities

**	****Seitz-Eastman Report  (NRC, 1984)**
**	****New facilities**
**	****6 Gev synchrotron radiation light source ****(APS)**
**	****Advanced, high-flux, steady-state neutron source ****(ANS, terminated in 1995)**
**	****1-2 Gev synchrotron radiation light source ****(ALS)**
**	****High-intensity pulsed neutron source**** (SNS)**
**	****Upgrades**
**	****Centers for cold neutron research incorporating guide halls and****	****instrumentation**
**	****Insertion devices at existing synchrotron radiation light sources**
**	****Experimental hall and instrumentation at LANSCE**
**	****Upgrades of the National Magnet Laboratory**
**	****Enriched pulsed neutron targets**** **
**	****Kohn Report  (DOE/BESAC, 1992)**
**	****Complete the design and construction of the ANS according to schedule**
**	****Immediately begin development of a 1 MW pulsed spallation source****	****(5 MW if the ANS is not continued)**
**	****Enhance operation and instrumentation of existing sources**
**	****Devise a strategy for sustained R&D of neutron instrumentation**
**	****Effectively manage proposed facilities to control regulations and to establish regulatory****	****responsibility; ER should assume responsibility for funding, cost control, and****	****construction of these facilities**

## Technical Specifications of the SNS

**	*****The Russell Panel (BESAC, 1996) specified a short-pulse spallation source in the 1 MW power range dedicated to neutron scattering with sufficient design flexibility such that it can be operated at a significantly higher power in a later stage.***
**The design must rely on low-risk technology initially.  In parallel, there is a critical need for R&D on ion sources, beam chopping, low energy beam transport, charge exchange injection, and moderator and target technologies to reduce risks to acceptable levels.**
**An initial instrument suite is required to maximize early scientific impact.**
**The linear accelerator design must not exclude direct injection of long pulses into a viable spallation target.**
**The facility must have a predictability and a reliability as set forth in the Kohn Report and must be capable of operating at least 240 days annually.**
**The facility should be commissioned in 2005.**

## What are Neutrons?  How are Neutron Beams Made?

***What are Neutrons?  How are Neutron Beams Made?***

## The Characteristics of Neutrons

**NEUTRONS HAVE NO ELECTRICAL CHARGE**
**Neutron cross sections for interaction with materials are small.  Therefore, neutrons are highly penetrating, nondestructive probes.  BUT, ... experiments are extremely flux limited.**
**Neutron interactions are known with great accuracy.  Therefore, neutron scattering data are more easily interpreted than comparable photon or electron scattering data.**
**NEUTRONS ARE SCATTERED BY NUCLEI, NOT BY ELECTRONS**
**Neutrons "see" both light and heavy atoms and can distinguish neighboring atoms in the periodic table.**
**Neutrons can distinguish isotopes of the same element, enabling isotopic substitution and contrast variation.**
**The large difference in neutron scattering cross sections for H and D facilitates studies of biological samples.**
**NEUTRONS ARE SPIN 1/2 PARTICLES**
**Spin polarized beams can be produced.**
**The neutron’s magnetic moment can probe microscopic magnetic structure and magnetic fluctuations.**
**NEUTRON WAVELENGTHS ARE COMPARABLE TO INTERATOMIC SPACINGS**
**Neutrons provide structural information over nine orders of magnitude (10****-5 ****to 10****4 ****Å), making them useful probes for distance scales ranging from the wavefunction of atomic hydrogen to those of macromolecules.**
**NEUTRON ENERGIES ARE COMPARABLE TO EXCITATIONS IN SOLIDS AND LIQUIDS**
**Neutrons provide energetic information on materials for transitions from the nanoelectron volt  to electron volts.**
**NEUTRON BEAMS HAVE LOW BRILLIANCE**

## Why High Flux?

**              *****HIGH FLUX MOVES EXPERIMENTS FROM:***
**	****• ****time constrained to  ...**
**	****	****	****	****...  doable**
**	****• ****cross sections to  ...**
**	****	****	****	****...  structures to  ...**
**	****	****	****	****	****...  dynamics to  ...**
**	****	****	****	****	****	****...  process and function**
**	****• ****simple systems to  ...**
**	****	****	****	****...  complex systems**

## The Need for the New, High-PowerSpallation Neutron Source

**The power of the SNS at 1 megawatt will be 6 times that of the world’s most powerful spallation source, which is ISIS in the United Kingdom.  The SNS is designed so that its power can be further increased when the technology is developed.  Why is high power so critical?**
***High power allows experiments to be done faster.***
**Currently all U.S. neutron sources are oversubscribed; about 800 users can be accommodated annually at the DOE’s four neutron sources.  The SNS *****alone***** will be used by about 2,000 scientists and engineers annually.**
**	****	**
***High power enables broad classes of experiments that simply cannot be done with low-power sources.***
**For example, high power enables studies of small samples, complex molecules and structures, time-dependent phenomena, and very weak interactions in many diverse disciplines -- physics, chemistry, materials science, geosciences, and biological and medical sciences.**