The n_TOF Collaboration, www.cern.ch/nTOF

Neutron Research at the n_TOF Facility (CERN)(for EC-CHANDA project)

Enrico Chiaveri

Spokesperson of n_TOF Collaboration

n_TOF facility at CERN

LHC (ex LEP)

SPS

PS complex n_TOF

n_TOF is a spallation neutron source based on 20 GeV/c protons from the PS of CERN from thermal to ~1 GeV neutron energy

n_TOF dedicated to measurements ofcapture and fission cross-sections for:• Nuclear Astrophysics (capture)• Nuclear Technology (capture and fission)• Fundamental nuclear physics

FP7 2013 CHANDA 2

C Rubbia et al., A high resolution spallation driven facility at the CERN-PS to measure neutron cross sections in the interval from 1 eV to 250 MeV, CERN/LHC/98-02(EET) 1998.

n_TOF: A spallation neutron source using the PS 20 GeV/c prot. beam

FP7 2013 CHANDA 3

NUCLEAR ASTROPHYSICS: stellar nucleosynthesisNeutron capture and (n, ) cross section of stable & unstable medium massisotopes playing a role in the s- and r-processes (1-300 keV).

NUCLEAR TECHNOLOGIES: ADS, Gen-IV and Th/U fuel cycleNeutron capture and fission cross sections of Actinides and Fission Fragments inthe thermal (meV), epithermal (eV-keV) and fast (MeV) energy ranges.

BASIC NUCLEAR PHYSICS: levels densities, -ray strength functions and ang. distributionsTime-of-Flight measurements with dedicated detectors provide very valuableinformation on basic nuclear physics quantities.

The n_TOF Collaboration30 Research Institutions from Europe, Asia and USA.

16 PhD students!

FP7 2013 CHANDA 4

n_TOF basic characteristics

FP7 2013 CHANDA 5

0,6·106 neutrons/pulse (capture mode)12·106 neutrons/pulse (fission mode)

High instantaneous intensity neutron beam with energy from thermal to 1 GeV

185 meters flight path, resulting in an excellent energy resolution

n_TOF basic characteristics

6

• n_TOF average flux comparable to GELINA (with 30 m flight path)

Average flux (n/sec) Instantaneous flux (n/pulse)

3 orders of magnitude!

Very high instantaneous neutron flux High proton intensity per pulse Spallation process

Great advantage in measuring radioactive samples (improved S/N ratio)

FP7 2013 CHANDA 7

The n_TOF activity

Capture25Mg, 54, 56,57Fe

58,60,62Ni, 63Ni,88Sr

236,238U

241Am

Fission240,242Pu

235U(n, /f)

232Th , 234U, 237Np ang.

distr.

(n, )33S, 59Ni

Capture151Sm

204,206,207,208Pb, 209Bi

24,25,26Mg

90,91,92,94,96Zr, 93Zr

186,187,188Os, 139La

232Th, 233,234U

237Np,240Pu,243Am

Fission233,234,235,236U

232Th, 209Bi

237Np

241,243Am, 245Cm

n_T

OF-

Ph

ase

1 (

20

01

-04

)

n_T

OF-

Ph

ase

2 (

20

09

-12

)

n_TOF-Phase 1

Papers: >50

Other publications: >150

EC projects:

FP5: n_TOF-ND-ADS

FP6: EUROTRANS

n_TOF-Phase2

Analyses ongoing

EC projects:

FP7: EFNUDAT

FP7: ERINDA

FP7: ANDES

n_TOF 2nd experimental area

n_TOF target

Newexperimental

area at 19 m (EAR-2)

Experimental area at 185 m

• Future EAR-2: flight path ~19 m at 90° with respect to the proton beam

FP7 2013 CHANDA 8

Beam Dump

EAR-2 Exp. Hall

Collimator

Magnet

Pit shielding

Target

New area

Existing area

The future: n_TOF vertical flight path at 20 m

FP7 2013 CHANDA 9

The main features of EAR 2

n_TOF target pit

ISR

101

102

103

104

105

106

107

10-12

10-10

10-8

10-6

10-4

10-2

100

dn /

dln

(E)

/ cm

2 /

7e1

2 p

pp

Neutron Energy [GeV]

Comparison of the Neutron Fluence in EAR1 and EAR2

EAR2EAR1

Maximum neutron fluence gain: x27 (keV region)

Higher fluence, by a factor of 25, relative to EAR1.

The shorter flight path implies a factor of 10 smaller time-of-flight.

Global gain by a factor of 250 in the signal/background ratio for radioactive isotopes!

The huge gain in signal-to-backgroundratio in EAR2 allows to measureradioactive isotopes with half lives as lowas a few years.

FP7 2013 CHANDA 10

The future: n_TOF vertical flight path at 20 m

x27

Experiments in EAR-2 can be performed :

i) on very small samples (reduce activity or used samples with limited availability)

ii) on isotopes with very small cross sections (where signal/background ratio is crucial)

iii) in much shorter time (some meas. can be eventualy repeated to reduce systematic )

iv) on neutron-induced cross sections at high energies (En>10-100 MeV), which are not

possible in the existing EAR-1, will benefit if the -flash is reduced.

v) possibility to bring a ‘basket’ with electronics component down to only 1.5 m from the

target (1010 neutrons/pulse): irradiation facility (e.g. SEE)

FP7 2013 CHANDA 11

Complementarity with NFS

FP7 2013 CHANDA 12

Average flux (n/sec) Instantaneous flux (n/pulse)

water-moderated

neutrons

neutrons in stellar

environments

kT = 5-100 keV

neutrons from

thermal fission

water-moderated

neutronsneutrons in stellar

environments

kT = 5-100 keV

neutrons from

thermal fission

Cost EAR-2

FP7 2013 CHANDA 13

kCHF Share (proposal)

Building 1.400 50% CERN + 50% n_TOF Coll.

Beam Line 450 50% CERN + 50% n_TOF Coll.

Services 1060 50% CERN + 50% n_TOF Coll.

DAQ (50x5000kCHF/channel) 310 50% EC + 50% n_TOF Coll.

Detectors (varii) 1265 50% EC + 50% n_TOF Coll.

Total (contingency 10%) 4.485 17% EC + 33% CERN + 50% n_TOF Coll.

EC proposed budget: 788 kCHFCERN budget: 1.500 kCHFn_TOF Coll. Budget:2.197 kCHF--------------------------------------------------TOTAL: 4485 kCHF

CH

AN

DA

n_TOF Collaboration:100 researchers30 institutions

Planning EAR-2

FP7 2013 CHANDA 14

FP7 2013 CHANDA 15

(Synchronisation &

slow control)

Control connection

Data stream

PACQ

Flash ADC

Disk server Disk server

Beam infos

Filter exchanger

BF3 counterDisk server

PACQ

Flash ADC

PACQ

Flash ADC

Run Control(User interface)

Producer

CASTOR(Tape storage)

Disk server

Limitations of present DAQ: Upgrades for EAR-2 (50 channels):8 bits flashADCs: 10-12 bits flashADCsdifficult to have low threshold and wide energy range

Memory/channel limited to 8 MB 64 MB/channelThermal (80ms) not reachable when sampling >100 MSsamples/s

Data transfer rate (<1 Gb/s): PCIeX4 (~10 Gb/s)Limited number of channels/stream

Existing DAQ consists on:54 flashADC channels of 8 bits 8MB memory

5 kCHF/channel= 250 kCHF

n_TOF DAQ upgrade

Parallel Plate Avalanche Counter (PPAC)

MicroMegas (MGAS) sCVD diamond (3x3 array)

BaF2 Total Absorption Calorimeter (TAC) Low neutron sensitivity C6D6

(n,c

hp

) re

acti

on

s(n

,xn

) re

acti

on

sn_TOF Detectors

FP7 2013 CHANDA 17

n_TOF@CHANDA

Task description Coordinator kEUR

Task 3.1 Design, mount and test a new DAQ for n_TOF-EAR2 CERN 310

Subtask 3.1.1 Define specifications and architecture n_TOF Coll.

Subtask 3.1.2 Purchase of DAQ channels n_TOF Coll. 250

Subtask 3.1.3 Development of the associated DAQ software (1 n_TOF member 1 year at CERN) n_TOF Coll. 60

Task 3.2 Equip to the new EAR-2 with the required detection systems CERN 365

Subtask 3.2.1 Neutron beam monitor systems based on Silicon detectors n_TOF Coll. 15

Subtask 3.2.2 Neutron beam monitor systems based on MGAS detectors n_TOF Coll. 15

Subtask 3.2.3 Charged particle detectors based on MGAS n_TOF Coll. 15

Subtask 3.2.4 Charged particle detectors based on an 10x10 array of sCVD diamonds n_TOF Coll. 200

Subtask 3.2.5 g-ray detection system for capture reactions 4xC6D6 n_TOF Coll. 20

Subtask 3.2.6 Standard g-ray detection systems on 2xHPGe n_TOF Coll. 100

Tasks 3.3 Design and build a new g-ray calorimeter capture reaction measurements N_TOF Coll. 900

Subtask 3.3.1 Design a new g-ray array based on new scintillator types n_TOF Coll.

Subtask 3.3.1 Built and characterize a demonstrator with a few modules (~5 modules) n_TOF Coll. 150

Subtask 3.3.3 Built and characterize the full array (~25 modules) n_TOF Coll. 750

TOTAL 1575