n_TOF Physics Report

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73^rd INTC meeting, CERN, 31/5/2023

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The EAR1 - NEL modification

Shorter neutron escape line (NEL)

• more space wrt the floor
• larger distance wrt the beam dump
• better background conditions from backscattered neutrons
• if needed we can always go back to the previous state
• the thickness of the window was measured

2022

2023

2023

Many thanks to O. Aberle, O. Fjeld

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EAR modifications

2022

2023

2023

New lightweight support frame with lift function useable for more applications

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Many thanks to O. Aberle, O. Fjeld

4

a-NEAR n_TOF activities

Measurement of the radiation background at the n TOF NEAR facility to study the feasibility of cyclic activation experiments (INTC-I-241)

Direct measurement of the n TOF NEAR neutron fluence with diamond detector (INTC-P-631)

Many thanks to A. Bernardes, O. Aberle, O. Fjeld

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i-NEAR n_TOF activities

• Large variety of samples installed at i-NEAR on Shelve or Rabbit positions
• Increased interest for more studies

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Many thanks to A. Bernardes, O. Aberle, O. Fjeld

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• 203 days of Physics started on 10th of April 2023, ending on 31st October 2023
• 7 days of FTN line commissioning started on 3rd April 2023
• 51 days of physics so far
• PoT: 5.3E18

2023 n_TOF beam - time schedule

before

after

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Some problems with SEM grid at the start of 2023 run

before

after

2022

Start of 2023 campaign when ppp>400E10

2023 after going back to the previous SEM grid el. chain

Beam start at 03.04.2023 - FTN line commissioning

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“Ringing” problem in EAR1

During the 2022 n_TOF campaign a (few shots) test was performed for the SADR detector.

The ringing problem was discovered. This is almost a showstopper for n,cp reaction studies in the MeV region (especially when the pulse shape particle identification technique has to be applied.

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before

after

SADR

2021

2022

Many thanks to A. Amaducci, S. Goula, L. Cosentino, ….

2021

2022

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Actions

• YETS: signal cables were separated from power cables and HV cables
• YETS: trace back any kind of changes in the cabling performed between 2021 and 2022
• First weeks of beam time fully devoted to identify and solve the problem

2022

2023

“Ringing” problem in EAR1

Many thanks to A. Amaducci, S. Goula, L. Cosentino, ….

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Actions with the beam

• Identify the problem (uMegas, HPGe, SIMON1, Si-det)
• Measure the current in different cables in the bunker
• Adding ferrites and additional grounding paths
• Optimizing grounding of the detector

“Ringing” problem in EAR1

Many thanks to A. Amaducci, S. Goula, L. Cosentino, ….

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before

after

HPGe test: (n,n’) reactions @ n_TOF

Two reactions were studied according to CERN-INTC-2021-025 ; INTC-I-230:

• ⁷Li(n,n’γ_478keV)
• ⁵⁶Fe(n,n’γ_847keV)

Many thanks to M. Bacak, C. Petrone, …

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before

after

HPGe test: (n,n’) reactions @ n_TOF

Setup:

• HPGe 27 % rel. eff
• Prototype equipped with switzer circuit
• At 125 deg, 20 cm distance, PE shielding

Many thanks to M. Bacak, C. Petrone, …

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before

after

HPGe test: (n,n’) reactions @ n_TOF

563 KeV ⁷⁶Ge(n,n’)

596 KeV ⁷⁴Ge(n,n’)

691 KeV ⁷²Ge(n,n’)

Many thanks to M. Bacak, C. Petrone, …

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before

after

¹⁸¹Ta(n,g) and Er(n,g) measurements in EAR1

Many thanks to V. Alcayne, …

¹⁸¹Ta(n,g) campaign finished last week. Some interesting results are already there!

• The capture cross section of Ta is important for nuclear reactors in space and fusion reactors.
• Recent critical experiments show discrepancies, that may indicate issues with the cross section of Ta.
• The previous data are discrepant and affected by important experimental corrections like the self-shielding or angular correlations between γ-rays.
• There are considerable differences between the recent evaluations.

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before

after

¹⁸¹Ta(n,g) and Er(n,g) measurements in EAR1

Many thanks to V. Alcayne, …

¹⁸¹Ta(n,g) campaign finished last week. Some interesting results are already there!

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NEAR: The first physics measurement successfully accomplished (CERN-INTC-2022-008 ; INTC-P-623))

Proof of principle study aiming to the extraction of MACS for challenging physics cases (even ~ng of sample material is enough!)

Many thanks to E. Stamati, A. Manna, A. Mengoni...

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NEAR: The first physics measurement successfully accomplished (CERN-INTC-2022-008 ; INTC-P-623))

Many thanks to E. Stamati, A. Manna, A. Mengoni...

• > 20 irradiations with different samples and B4C thicknesses (>6 months irradiation time, >20 interventions)
• > 8 months of gamma spectroscopy data taking at GEAR

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before

after

Upcoming measurements

• EAR1:
• ²⁴³Am(n,f), CERN-INTC-2020-048 ; INTC-P-566
• ^natEr(n,g), CERN-INTC-2023-015 ; INTC-P-656
• ³⁰Si(n,g), CERN-INTC-2023-009 ; INTC-P-653
• ¹²C(n,cp) - SADR, CERN-INTC-2022-019 ; INTC-P-629
• ¹²C(n,cp) - DDX, CERN-INTC-2020-061 ; INTC-I-221

• EAR2:
• ²⁴³Am(n,f), CERN-INTC-2020-048 ; INTC-P-566
• ³⁰Si(n,g), CERN-INTC-2023-009 ; INTC-P-653
• ⁶⁴Ni(n,g), CERN-INTC-2022-033 ; INTC-P-208-ADD-1

• NEAR:
• Diamond measurement, CERN-INTC-2022-022 ; INTC-P-631
• Background measurement, CERN-INTC-2022-018 ; INTC-I-241

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before

after

Conclusions

• Target performance as expected, FTN beam line modifications successful (SEM cabling reversed to 2022 situation),
• Thanks to the excellent work done by ABT, OP, BI and RP (+STI), large beam spot on target (and its continuous monitoring via SEM grid) is now available
• This optimisation, coupled with efficient (gas) cooling systems and target thermocouples, allows for target average power increase (166*10¹⁰ p/s to 220*10¹⁰p/s)
• The ringing problem that was improved but not solved. On the detector side we know well what to do to suppress this problem. Antenna measurements and more investigation is needed on the facility side.
• We had a smooth starting of the 2023 with important achievements already (e.g. neutron inelastic measurements are feasible @n _TOF, NEAR first physics measurement, …)
• PoT as expected. Many thanks to the PS teams!
• A busy 2023 campaign is in front of us!

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Thank you

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before

after

2021

2022

SIMON1

The problem was there in all silicon detectors (and HPGe).

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“Ringing” problem in EAR1

Many thanks to A. Amaducci, S. Goula, L. Cosentino, ….

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Results:

• There is space of improvement with respect the sorting of cables (HV, power, signal, infrastructure cables, etc)
• The length of cables is important. Mounting the PA directly in the detector board or in the flange will reduce or even eliminate the ringing problem.
• Ferrites and improved grounding is important. A factor of 2 reduction of ringing problem was observed through a combination of ferrites and additional grounding paths
• Cables show different noise behavior: There are signal cables showing good noise behavior and others more “noisy”.
• Detector already in INFN - LNS for refurbishment
• We will be ready to go ahead with CERN-INTC-2022-019 ; INTC-P-629 “Measurement of (n,cp) reactions in EAR1 and EAR2 for characterization and validation of new detection systems and techniques”

“Ringing” problem in EAR1

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2023 n_TOF beam - time schedule

before

after

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