The PPAC neutron monitoring for EAR2 L. Tassan-Got, L. Audouin, C. Le Naour,

C.O. Bacri

CACAO, NEEDS

IPN Orsay-France

I. Duran , E. Leal, E. Casarejos (UVigo)

Santiago de Compostela - Spain

nTOF Technical. Meeting, CERN - March 2014

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The PPAC neutron monitor for EAR-2

In my last presentation of Sept 2013, the idea was to place the PPACs monitor by the top of the EAR2 cave.

The present idea is to place it by the floor, just on the collimator exit.

The present setup is a provisional one, because the lack of the specific targets and PPACs force us to use some spare parts and targets already used for EAR1.

Conceptual drawing

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3 PPACs 2 Targets Delay lines + fast current amplifiers(2 stripped cathods Low-pressure chamber

and 1 central anode) oows 8 cm diam. windows

X

Y

20 x 20 cm

Pile up of X-Y signals at EAR2

shorter delay-lines + faster amplifiers

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(Signals taken from the EAR1 setup)

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Working plan

In order to cope with the very short time scheduled for the commisioning:

- 2 U5 targets available … but having the EAR1 (biggest) dimensions! - 2 spare PPACs available + 2 more borrowed from EAR1This force us to construct a provisional gas-chamber (big enough) - gas system borrowed from EAR1 (a new one is coming)

The new setup will follow, with new targets and new PPACs (much smaller)

- To make specific targets adapted to the smaller collimator.

- To construct a new gas chamber for up to 3 targets, with 2, 3 or 4 PPACs

- To make new PPACs for the EAR2 monitoring

- To implement a new front end electronics to stand with the high counting rate

- To construct a new dedicated gas regulation

Time table (updated)

a) engeenering (Quantum, Vigo)

b) Vessel mechanical construcction

c) assembling at IPNO (provisional gas system)

d) Electronics

e) test at IPNO

f) new gas system

a)

b)

c)

d)

e)

f)

Dec Jan Feb Mar Apr May Jun Jul Aug Sep

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Beam profile with PPACs

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Two examples from the past campaigns. Samples of U-235, 8cm dia. and of Bi-209 deposited over the whole backing.

Both are covering well the smaller beam spot and the halo at EAR2

The cathode strips pitch is 2 mm The resolution is of the same order

209Bi235U

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Mechanical design (this version)

The PPACs having the same dimensions as in EAR1,their cradle has been reduced only in heigh.

The gas chamber size is 510 x 470 cm2. The high is reduced to 300 cm.

Actualy it is designed to hold up to 3 targets with 4 PPACs (3 PPACs if 2 targets)

5 FADC channels are required for each PPAC (one for the anode and 2 for each cathode) Two targets will require 15 chans.

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New design for the provisional setup

The chamber is made of three parts:The lower one with all the interfaces;The cradle to support targets and PPACs;And the hood made as ligth as posible,The total weigh is: 15 kg of Al 2 kg of fiberglass 1 kg of others

.

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Two PPACs are available and two more are under way (15 k€)

New targets are to be done (5 k€ requested from nTOF)

The electronics is being modified in order to cope with the higher rate (of about ten times) IPNO is doing funded by NEEDS.

Gas regulation: there is one system being used by the EAR1 PPACs chamber, that can be used at the beginning another system must be done at around 5 k€ (USC ?)

A new chamber (5 k€) to be done at Vigo Flanges, windows, cabling pass-through, Power Supplies, … : (15 k€ are requested to the 2013 Spanish Ministry funds … still pending!)

Conclusions

- The PPACs n-flux Monitor is on schedule

- The required space must be allocated by the floor, including room for the gas system (the same as in EAR1)

- The impact on the background is minimised … it must be estimated, nevertheless.

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EXTRA SLIDES