Beam Monitors with GEM detectors Balla, Buonomo, Ciambrone, Corradi, Ferrari, Murtas, Mazzitelli, Quintieri, Tagnani Laboratori Nazionali di Frascati INFN Bhabha tracker for Dafne Upgrade Neutron High Flux monitor Beam monitor for Beam Test Facility An R&D project of INFN : IMAGEM http://www.lnf.infn.it/esperimenti/imagem/

Bhabha Tracker Luminometer At Dafne IP1 (ex KLOE) has been installed the Siddharta experiment. The runs will be used also for Crab Waist studies (for Super B) Good luminosity measurements are requested. 3GEM Luminometer e+ e-  e+ e-

LUMI GEM Assembling Seven detectors have been built Pads : 6 x 24/32 mm2 Seven detectors have been built pads induction gap GEM 3 GEM 2 GEM 1 Cathode Mother board Final luminometers with Carioca FEE

GEM luminometer mounted on IP The detectors were displaced 5 mm towards the machine center Electron monitor Positron Monitor 3 5 mm 1 4 3 1 2 4 2

Background monitor Readout every second with VME scalers 28 KHz Only 1 Only Electron Beam Electron monitor 2 3 Positron Monitor 48 KHz 4

During injection 1100 KHz 400 mA 345 KHz

Bhabha time correlation x 1 4 Readout multihit TDC Single event theta phi

Bhabha Correlation The correlation in phi of bhabha events is clear time Hz The correlation in phi of bhabha events is clear More precise analysis is in progress time time The system is able to measure the particle impact point with a precision of 8 mm in theta

Neutron Monitor

Neutron flux monitor with triple GEM Experimental Setup at FNG (Enea Frascati) 2.4 MeV (DD) 14 MeV (DT) from fusion reaction

Neutron Monitor n p Event display (1 second time gate) Polyethylene (2mm) 64 pads 10x6 mm2 38.4 cm2 Alu (0.2 mm) p Ar CO2 CF4 3 mm Event display (1 second time gate) Online neutron flux vs time neutron source spot light

Flux vs time GEM hit frequency NE213 measurements (KHz) The nominal neutron flux is measured with a NE213 placed about 10 meters far form the gun GEM hit frequency NE213 measurements This is the flux measurement at the working point of 1110 V (gain = 300) The number of hits measured by the GEM chamber follow more precisely the flux measured by the NE213 Beam Stop time (min)

Comparison between GEM and NE213 Neutrons on detector (38 cm2) GEM Counts (KHz) 22 MHz 5.3 MHz s = 0.2 s = 0.4 s = 0.3 s = 0.9 Time (min) Beam Stop Counts (KHz)

Event Display The acquisition gate has reduced to study the cluster size for each neutron : Two event displays with few neutrons hitting the chamber event 114 event 129 cluster size 1.28 pads

Photon Background At the working point (Gain 300) neutron working point working point At the working point (Gain 300) the contamination from photons is practically zero

Calibration and Linearity The efficiency mesurement are in agreement with MC prediction = 4.1 x10-4 Hits on detector (KHz/cm2) A test on FTU (Frascati Tokamak Upgrade) is foreseen before the end of this year. Higher neutron flux beam are needed to measure the real performance o this monitor Neutrons on detector(MHz/cm2)

Small TPG for beam monitor

TPG for beam diagnostic It’s essentially a small TPC with a 4 cm drift and readout with triple GEM In this way also high current beam can be monitored in position box cross section Particle beam Triple GEM structure Without magnetic field FEE electronics A preliminary field cage built for recover the field distortion

Horizontal and Vertical Beam profile Y position 16 pads 6 mm X position 4 pads 10 mm BTF vertical beam profile sybeam (3.7 mm) 2000 tracks Yposition (mm)

TPG performance The track is reconstructed using the space time relation single event with two tracks sy (208 mm) residual distribution Yposition (mm) Y(pads) top view (1) (2) Z(mm) side view (1) pads Z(mm) side view (2)

Electronics developed

HV supply for GEM detectors HVGEM is a new device designed and realized at Frascati specifically for the HV power supply of 3GEM detectors. All the detector for beam diagnostic has been power up with this new device G3 G2 G1 Cathode (up to 5 KV) Controlled via Canbus A Corradi, F. Murtas and D.Tagnani A novel HighVoltage System for a triple GEM detector Nuclear Inst. and Methods in Physics Research, A Reference: NIMA46128 15 V

New system with 4 modules Recently a new system with 4 modules has been made for the luminometer power supply. This system is actually working near the Dafne IP A detail of 4 HV connectors

New 16 channels card The card has been designed and realized (Gianni Corradi) Total dimension : 3x6 cm2 Channel density of 1 ch/cm2 Sensitivity of 2-3 fC; LVDS output (25 ns); Radhard; Extremely modular and usable for other GEM applications Up to now they have been used on: The Cylindrical GEM for Kloe Inner tracker prototype GEM track luminometer two possibility : for output connectors out in out PCB

Carioca GEM FE board GEM track luminometer for DAFNE Upgrade New chamber with 128 channels

“Intelligent” Mother Board It has already designed a Mother board 12x12 cm2 for Low and High Voltage distribution and able to receive directly the signal coming from Carioca Cards 128 ch. We are working on a Intelligent Mother Board with an FPGA on board able to count the 128 channel hits and/or measure the time respect to a trigger (1 ns) ; the data are readble through an ethernet connection. LV Trigger FPGA Ethernet FEE card LVDS Digital Outputs Carioca Carioca FEE card FEE card Inputs Carioca Carioca Inputs

Conclusions Several detectors based on triple GEM technology have been built in Frascati for several purpose : Bhabha track position, Neutron monitor, Beam monitors, Xray, Gamma ray … In all of these sectors they show good performances and confirm good radiation hardness These R&D brought us to develop new HV systems and new front end electronics based on well known chips (ASDQ & Carioca GEM). Future R&D is foreseen on neutron detection for high fluxes (Nuclear Fusion Reactors) in collaboration with ENEA Frascati Tokamak New electronics for “on board DAQ” based on FPGA

Design for Bhabha Luminometer 4 semi anular detectors with 32 pads each with a total diameter of 20 cm. PAD PCB (6 x 23-34 mm2) Front side On the back side the places for 2 FEE cards Back side

Kapton foil with 3 lumi GEM The construction of this type of detector has required a new GEM design (same kapton and holes structure but different electrodes shapes ) One GEM foil with the three annular structure during the stratching phase for the prototype construction

Hit molteplicity and timing Without T0 subtraction Over 32 channels 1.27 11 ns Molteplicity 12 ns 1.28

HV Online monitor and control HVGEM system Console It gives the possibility to set and control directly the 4 fields and the total gain of our triple GEM chambers

LHCb HVGEM System On September 2007 a new HV system for LHCb GEM chamber has been built in Frascati and installed at CERN for a total of 24 HV modules and 24 nano Ammeter . 24 Ammeter modules on the crate upper side 24 HV modules (7 ch each) on the crate lower side

HVGEM prototype stability s < 1V Volts Daq days Volts g2 s < 1V Volts Daq days Volts s < 1V Volts g3 Daq days Volts Good gain stability !