中文  
Home │ About Us  
 
Introduction
TEXT SIZE: A A A

1 Scientific Significance

Neutron, like x-ray, is a powerful means to probe the structure of the microscopic world. Moreover, neutron has some special properties that x-ray does not possess: 1)neutron bears with no charge, but with magnetic vector; 2)neutron owns high ability of penetration through a matter; 3)neutron is much more sensitive to light element and isotopes; 4)neutron can detect both the structure and dynamics behavior of a matter. For these reasons, neutron scattering becomes a complementary means to x-ray in the advanced researches in physics, chemistry, biology, life science, material science, new energy, as well as in applications.

Two high performance x-ray sources based on synchrotron radiation facility are operated for users at Beijing (BSRF at IHEP) and Hefei (NSRF at USTC), and another new one is completed in Shanghai (Shanghai Light Source). However there is no high performance pulsed neutron source in China. To meet the increasing demand from user community, China decided to build a world-class spallation neutron source, called CSNS. It can provide users a neutron scattering platform with high flux, wide wavelength range and high efficiency. The pulsed-beam feature allows studies not only on the static structure but also the dynamic mechanisms of the microscopic world. The high-flux pulsed neutrons, muons, and protons from CSNS will also complement continuous-wave neutrons from the China Advanced Research Reactor (CARR).

updated from Neutron Scattering, K. Skold and D.L. Price: eds., Academic Press. 1986

2 Facilities

CSNS mainly consists of an H- linac and a proton rapid cycling synchrotron. It is designed to accelerate proton beam pulses to 1.6 GeV kinetic energy at 25 Hz repetition rate, striking a solid metal target to produce spallation neutrons. As shown in Table 1, the accelerator is designed to deliver a beam power of 100 kW with the upgrade capability to 500 kW by raising the linac output energy and increasing the beam intensity.

Schematic layout of CSNS facilities

 Table 1 CSNS primary parameters in baseline

Project phase

I

Beam ave. power, kW

100

Proton energy, GeV

1.6

Ave. current, I, µA

62.5

Repetition rate, Hz

25

Proton per pulse, 1013

1.63

Pulse length, ns

<500

Linac energy, MeV

80

Linac peak current, mA

15

Target material

Tungsten

No. Moderators

3

No. neutron instruments

3

 

2.1 Accelerator

 
    Four vane type high-intensity RFQ accelerator
 
   Dipole magnet for beam bending in the RCS

Negative hydrogen ions (H-) are firstly generated from a Penning ion source. RFQ accelerator forms beam bunches at 324 MHZ RF frequency and accelerates the beam to 3 MeV. The four-vane RFQ is similar to the one previously developed at IHEP for the ADS program. Four DTL tanks further increase the beam energy to 81 MeV. A long beam transport line is followed with the DTL linac to send the beam a rapid cycling synchrotron (RCS) accelerator. In this beam line, a sufficient space is reserved for the additional linac structures, such as DTL tanks or superconducting linac, for the power upgrade in future. The H- beam is stripped to become proton beam and injected into the RCS ring. In the ring the proton beam is accumulated to a high current pulse and then accelerated to 1.6 GeV.

2.2 Target

The high-energy proton beam extracted from the accelerator bombards on the target to generate neutrons through spallation reaction. Tungsten is used as the target material with heavy water as the cooling media. The high-energy neutrons are then cooled down by moderator to become thermal or cold neutrons, which meet for the neutron scattering experiments.

For the CSNS target station design, the target team had chosen an all-horizontal target/moderator/reflector arrangement in 2009. The horizontal trolley that contains most of all the active components in a single assembly that can be easily retracted into the target remote handling cell. It also reduces the complexity of the shielding and reduces the need for overhead handling.

2.3 Instruments

CSNS’ first target station accommodates at least 18 neutron scattering instruments. However, due to limited project funds, only three day-one instruments are supported: a high intensity diffractometer, a broad Q-range small angle diffractometer, and a multi-purpose reflectometer. Efforts are made to attract interested institutes and universities to invest in dedicated neutron instruments.

T0 neutron chopper for a clear background ---------------- Design of the high intensity diffractometer       
 

3 Schedule

CSNS construction is expected to start in 2010 and will last 6.5 years. Facility commissioning will take about 1.5 years to reach the specified beam power on the target and neutron flux. The normal operation for users is foreseen in 2018.

4 Site

CSNS construction site locates at Dongguan, Guangdong province. It is about 85 km from Guangzhou and about 125 km from Hong Kong. IHEP will set up a new branch on the present green field. CSNS will be the first large scientific facility in the south China where the economy grows very rapidly. It is expected the CSNS construction and operation will have positive effects in promoting the sciences and high-tech development in the area.

 

 
Copyright ©2002-2010 CSNS Project Office.
Questions and Comments to zhaojs@ihep.ac.cn