PERFORMANCE OF A PARALLEL PLATE

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712

SplSSN614-087-X

PERFORMANCE OF A PARALLEL PLATE

- Bizzeti, A. Universita and Sezione INFN di Firenze, Firenze, Italy. - Civinini, C. " "

- D'Alessandro, R. " "

- Ferrando, A. CIEMAT, Madrid, Spain

(Under CICYT Grants: AEN91-1283-E and AEN92-0829) - Malinin, A. ITEP, Moscow, Russia.

- Martínez-Laso, L. CIEMAT, Madrid, Spain

(Under CICYT Grants: AEN91-1283-E and AEN92-0829) CERN, Geneva, Switzerland.

- Pojidaev, V. Universita and Sezione INFN di Firenze, Firenze, Italy.

CENTRO DE INVESTIGACIONES

ENERGÉTICAS, MEDIOAMBIENTALES Y TECNOLÓGICAS

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CLASIFICACIÓN DOE Y DESCRIPTORES 662000/440104

CHARGED PARTÍCLE DETECTION CALORIMETRY

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Toda correspondencia en relación con este trabajo debe dirigirse al Servicio de Información y Documentación, Centro de Investigaciones Energéticas, Medioam-bientales y Tecnológicas, Ciudad Universitaria, 28040-MADRID, ESPAÑA.

Las solicitudes de ejemplares deben dirigirse a este mismo Servicio.

Los descriptores se han seleccionado del Thesauro del DOE para describir las materias que contiene este informe con vistas a su recuperación. La catalogación se ha hecho utilizando el documento DOE/TIC-4602 (Rev. 1) Descriptive Cataloguing On-Line, y la clasificación de acuerdo con el documento DOE/TIC.4584-R7 Subject Cate-gories and Scope publicados por el Office of Scientific and Technical Information del

Departamento de Energía de los Estados Unidos.

Se autoriza la reproducción de los resúmenes analíticos que aparecen en esta publicación.

Este trabajo se ha recibido para su impresión en Octubre de 1992

Depósito Legal n° M-19909-1993 I.S.B.N. 84-7834-203-6

I.S.S.N. 614-087-X

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1. INTRODUCTION.

The requirements for detectors in the forward and very forward región of future hadron colliders experiments are very demanding. The detector should be fast, work in áreas of very high occupancy [1], under serious radiation levéis [2] and be simple and cheap due to the large volume to cover.

A detector based on the parallel píate chambers (PPC) principie [3] can be considered a satisfactory solution.

A PPC detector consists of two metallic fíat electrodes (planarity better than 5 u.m is needed). The small and precise gap (sizes ranging from 1 to 2 mm, with an accuracy of 5 Jim) is filled with a gas. It works in the avalanche mode with very uniform electric fields of 30 to 60 kV/cm, depending on the gas and gap used. The PPC detector propertiesand their use for calorimetry have been discussed elsewere [4-5].

These detectors have, among other properties, the following main features:

- High rate capability (no saturation effects observed at rates of 108 particles/s cm2 for similar devices [6]),

- Very fast signal (rise time less than 1 ns and fullwidth of the electrón collection smaller than 2-3 ns) [7],

- Radiation resistance (made of radiation-hard naterials, as the large surface of PPC electrodes is afew orders of magnitude grater than that for the anode wires, the ageing effects in a PPC are negligible).

Among the possible technologies for building these detectors, we consider the use of thick iron electrodes as a reasonable solution for a calorimeter, suitable in very strict working conditions.

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and gaps, filled with the adequate gas which can act as active sampler. The whole module is kept in a gas tight volume. The spacers to define the gas gap and insulator materials can be made of ceramics.

To test the viability of such idea we have built a prototype of a parallel píate volume cell which will be described below and we have performed some tests with cosmic rays, to study different gas mixtures, stability and behaviour during few months of measurements.

The adequate gases or mixture of gases for the very forward calorimetry should be not flammable and with low hydrogen content to reduce the kake signal of recoil protons from the incoming hadrons. The voltage applied to the electrodes should be low enough, the gas should have no photon feedback and the breakdown probability should be very low. The collected charge and efficiency for MIP's have to be above the limits required for calorimetry.

2. PRQTOTYPE DESCRIPTION.

The main elements of the prototype are shown in fig. 1. It is made of three polished iron plates 17 mm thick. Two of them have a surface of 180x180 mm2 and they are used as ground electrodes. The third one has a surface of 130x130 mm2 and it is used as intermedíate electrode connected to the high voltage. All the edges of this high voltage elctrode have been carefully rounded and polished. The detector is assembled as a sandwich with the central high voltage electrode contained between the two ground electrodes. Some precise spacers made of plexiglass with a thickness of 1.5 mm ± 5 (im define the gas gap between electrodes. The gas thightness is achieved using a plexiglass frame with the high voltage connection and the gas inlet and outlet. The assembly was done in a dust free room using puré water for electrode surface cleaning.

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despite the electric noise coming from the intrinsic capacitance of the detector, of the order of 200 pF.

The amplifier (SPNPI-921-1-M), already used in [7], has slow rise time (7 ns) and high gain (60 mV/(iA) and relatively low noise (3000 electrons).

3. EXPERIMENTAL SETUP.

The experimental setup used for this work is schematically shown in fig. 2.

The prototype described in the previous section was located horizontally between the two scintillating counters used for trigger. The active área of the counters was 80x80 mm2. The cosmic rays rate was about 0.2 Hz. The time of flight difference between the two scintillators was measured and an online cut of 4 ns was used for a clean cosmic trigger selection.

The data acquisition system consisted of a CAMAC crate containing a LeCroy 2249A ADC module for PPV cell charge measurements and a LeCroy 2228 TDC for time of flight. A VALET V3 system was used for data acquisition using a Macintosh SE as user interface.

The analog signal from the PPV cell was digitized and stored for each accepted trigger from the counters for a set of different voltages.

4. RESULTS.

In fig. 3 the ADC charge spectrum for CO2 at 5.6 kV is shown in comparison with the superimposed pedestal (o = 12 ADC counts). The efficiency of the chamber is given by the ratio of the number of events above the pedestal valué to the total number of events. To discrimínate between pedestal and signal events in the ADC spectrum a cut at two standard deviations from the mean valué of the pedestal has been applied.

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The highest efficiency, 65% is obtained for CO2 (fig. 4a). A plateau is seen in the región 5550 to 5600 V. With CF4, a similar valué for the efficiency is obtained at 5820 V, without reaching a plateau región before the breakdown point. Note that both gases presesnt some photon feedback and secondary avalanches are often observed in the chamber. To reduce this effect we have doped CO2 with 1% isopropilic alcohol (open circles in fig. 4a). The efficiency obtained is 5% smaller and secondary avalanches are still present.

The chamber was finally tested with a mixture of Ar-CH4 (80%-20%) (fig. 4b). The máximum efficiency is 56% at 3100 V and now the photon feedback is strongly reduced by the presence of the methane. This mixture allows the use of low voltages, which simplify the design of big detectors, reducing cable shielding and insulators. However, the presence of hydrogen molecules induces breakdowns at working voltages; when this happens the high voltage must be reduced and slowly increased.

The mean collected charge is given in fig. 5 a) and b) for the various gases. All of them converge to a valué of about 20 fC for the máximum working voltage.

5. CONCLUSIONS.

The thick iron electrode technology has been tested as a possible approach to build calorimetric modules.

The performance of a PPV cell prototype has been studied. The system has worked during months with CO2 as detection gas.

The use of puré CO2 satisfies the requirements for calorimetry working at modérate high voltages with good efficiency (65%) and collected charge (20 fC) for minimum ionizing particles. The photon feedback can be reduced including a small percentage of quencher.

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6. ACKNOWLEDGEMENTS.

We acknowledge the support from the following funding agencies: CIEMAT, Madrid, Spain; CICYT, Spain; INFN, Firenze, Italy and ITEP, Moscow, Russia.

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REFERENCES.

[1] "The Mínimum Bias Environment in the Very Forward Región of CMS".

A. Ferrando et al., CMS Technical Note TN/92-21, July 1992.

[2] "The estimation of parameters of radiological interest in and around an LHC experimental área".

G.R. Stevenson et al, CERN/TIS-RP/IR/92-06, February 1992. [3] "The Parallel Píate Chambers as a detector for Fast, Radiation Resistive Calorimetry".

Yu. Galaktionov et al., Nucí. Instr. and Methods A317 (1992) 116. [4] "Very Forward Calorimetry for CMS: An iron/gas sampling" calorimeter approach".

A. Ferrando et al., CMS Technical Note TN/92-19, February 1992. [5] "Notes for a CMS Letter of Intent concerning: Very Forward Jet Tagging simulation, Very Forward Calorimetry and Forward Muon Trigger".

A. Ferrando et al., CMS Technical Note TN/92-23, July 1992.

[6] "The Microstrip Gas Avalanche Chamber: A New Detector for the Next Generation of High Luminosity Machines".

F. Angelini et al., Proc. ECFA Study Week on Instrumentation Technologies for High Luminosity Hadron Colliders; CERN 89-10, ECFA 89 124, 1989, Vol. II, page 465.

[7] "Construction and Performance of Parallel Píate Chambers Prototypes".

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FIGURE CAPTIONS.

Fig. 1: Elements of the prototype: a) Electrodes surface,

b) Gas gaps.

Fig. 2: Sketch of the experimental set-up for measurements with cosmic rays.

Fig. 3: ADC spectra at 5600 V with CO2..

Fig. 4: Detection efficiency (%) for MIP's, as a function of the high voltage, for:

a) CO2, CO2-isopropil doped, and CF4, b) Ar - CH4 (80% - 20%) mixture.

Fig. 5: Mean collected charge for MIP's, as a function of the voltage, for:

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10 CM

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CIEMAT-712

Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas Instituto de Investigación Básica.- Madrid.

"Performance of a parallel píate volume cell prototype for a fast iron/gas calorimeter11.

BIZZETI,A.; CIVININI,C.; D1ALESSANDRO,R.; FERRANDO,A.; MALININ,A.; MARTINEZ-LASO,L.;

POJIDAEV.V. i 1993) 20 pp. , 5 f i g s . , 7 r e f s .

We present the f i r s t t e s t of the application of the p a r a l l e l p í a t e chamber p r i n c i p i e s for the design of a very fast and radiation-hard iron/gas sampling calorimeter, s u i t a b l e for very forward regions in d e t e c t o r s for LHC, based on the use of thick iron p l a t e s as e l e c t r o d o s .

We have b u i l t a one c e l l prototype consisting of three p a r a l l e l thick iron p l a t e s (17 mm e a c h ) . Results on e f f i c i e n c i e s and mean c o l l e c t e d charge for mínimum ionizing p a r t i d o s with d i f f e r e n t gases are presented.

DOE CLASSIFICATIÓN AND DESCRIPTORS: 662000/440104. Charged p a r t i c l e Detection. Coloriraetry. Hígh Energy Physics. Hadrons.

CIEMAT-712

"Performance of a parallel píate volume cell prototype for a fast iron/gas calorimeter".

BIZZETI,A.¡ CIVININI,C.; D'ALEESANDRO,R.; FERRANDO,A.¡ HALININ.A.; MARTINEZ-LASO,L.¡ POJI0AEV,V. (19931 20 p p . , 5 f i g s . , 7 r e f s .

We present the f l r s t t e s t of the application of the p a r a l l e l p í a t e chamber p r i n c i p i e s for the design of a very f a s t and radiation-hard iron/gas sampling calorirooter, s u i t a b l e for very forward regions in d e t e c t o r s for LHC, based on the use of thick iron p l a t e s as e l e c t r o d e s .

We have b u i l t a one c e l l prototype consisting of three p a r a l l e l thick Iron p l a t e s (17 mm each}. Results on e f f i c i e n c i e s and mean c o l l e c t e d charge for minijnum ionizing p a r t i c l e s with d i f f e r e n t gases are presented.

DOE CLASSIFICATION AND DESCRIPTORS: 662000/440104. Charged p a r t i c l e Detcction. Colorimotry. High Energy Physics. Hadrons.

CIEMAT-712

Centro do Investigaciones Energéticas, Medioambientales y Tecnológicas Instituto de Investigación Básica.- Madrid.

BIZZ£TX,A.; CIVININI,C; D'ALESSANDRO,R.; FERRANDO,A.; MALININ,A.; MARTINEZ-LASO,L.; POJIDAEV,V. (1993) 20 p p . , 5 f i g s . , 7 r e f s .

We present the f i r s t t e s t of the application of the p a r a l l e l p í a t e chamber p r i n c i p i e s for the design of a very f a s t and radiation-hard iron/gas sampling calorimeter, s u i t a b l e for vory forward regions in d e t e c t o r s for LHC, based on the use of thick iron p l a t e s as e l e c t r o d o s .

Wo have b u i l t a one c e l l prototype consisting of three p a r a l l e l thick iron p l a t e a (17 mm e a c h ) . Results on e f f i c i e n c i e s and mean c o l l e c t e d charge for mínimum ionizing p a r t i c l e s with d i f f e r e n t gases are presented.

DOE CLASSIFICATIÓN AND DESCRIPTORS: 662000/440104. Charged p a r t i c l e Detection High Energy Physics. Hadrons.

Colorimetry.

CIEMAT-712

BIZZETX,A.; CIVININI,C; D'ALESSANDRO,R.; FERRANDO, A.; MALININ,A.; MARTINEZ-LASO,L.; POJIDAEV,V. (1993) 20 p p . , 5 f i g s . , 7 r e f s .

We present the f i r s t t e s t of the application of the p a r a l l e l p í a t e chamber p r i n c i p i e s for the design of a very f a s t and radiation-hard iron/gas sampling calorimeter, s u i t a b l e for very forward regions in d e t e c t o r s for LHC, based on the use of thick iron p l a t e s as e l o c t r o d e s .

We have b u i l t a one c e l l prototype consisting of three p a r a l l e l thick iron p l a t e s '{17 rnm e a c h ) . Results on e f f i c i e n c i e s and mean c o l l e c t e d charge for mínimum ionizing p a r t i c l e s with d i f f e r e n t gases are presented.

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CIEMAT-712

Centro do Investigaciones Energéticas, Medioambientales y Tecnológicas

Instituto de Investigación Básica.- Madrid. 1

"Prestaciones de una celda prototipo de un volumen de ¡ placas paralelas para un calorímetro rápido de hierro y ¡ gas. "

1 UIZZETI,A.; CIVININI,C.; D ' ALESSANDRO, R. ; FERRANDO,A.; MALININ,A.; MARTÍNEZ-LASO, L. í

POJIDAEV.V. (1993) 20 p p . , 5 f i g s . , 7 r e f s . 1 Presentamos l o s primeros t e s t s de l a a p l i c a c i ó n de la técnica de cámaras do p l a c a s para

1 l e l a s en e l diseño de un c a l o r í m e t r o de muestreo de h i e r r o / g a s , muy rápido y r e s i s t e n t e a

La r a d i a c i ó n , que s e r l a adecuado para su u t i l i z a c i ó n en l a s regiones muy hacia a d e l a n t e de l o s d e t e c t o r e s LHC y basado en e l uso de p l a c a s de h i e r r o de gran e s p e s o r .

Hemos construido una celda p r o t o t i p o c o n s i s t e n t e en t r e s p l a c a s p a r a l e l a s de h i e r r o (17 mm de e s p e s o r ) . Presentamos l o s r e s u l t a d o s sobre e f i c a c i a s de detección y colección de carga para p a r t í c u l a s mínimamente i o n i z a n t e s .

1 CLASIFICACIÓN DOE Y DESCRIPTORES: 662000/44010'!. Charged P a r t i c l e Detection. Caiorimetry.

High Energy Physics. Hadrons.

*

| _ _ _ — — — —

-! CIEMAT-712

¡

' Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas

1 Instituto de Investigación Básica.- Madrid.

» "Prestaciones de una celda prototipo de un volumen de i placas paralelas para un calorímetro rápido de hierro y ¡ gas."

1 BIZZETI,A.; CIVININI,C.; D'ALESSANDRO,R.; FERRANDO,A.; MALININ,A.; MARTINEZ-LASO,L.; 1 POJIDAEV,V. (1993) 20 p p . , 5 f i g s . , 7 r e f s .

1 Presentamos l o s primeros t e s t s de l a a p l i c a c i ó n de la t é c n i c a de cámaras de p l a c a s para 1 l e l a s en e l diseño de un c a l o r í m e t r o de muestreo de h i e r r o / g a s , muy rápido y r e s i s t e n t e a ' l a r a d i a c i ó n , que s e r í a adecuado para su u t i l i z a c i ó n en l a s regiones muy hacia a d e l a n t e ' de l o s d e t e c t o r e s LHC y basado en e l uso de p l a c a s de h i e r r o de gran e s p e s o r .

' Hemos c o n s t r u i d o una celda p r o t o t i p o c o n s i s t e n t e en t r e s p l a c a s p a r a l e l a s de h i e r r o ' (17 iian de e s p e s o r ) . Presentamos l o s r e s u l t a d o s sobre e f i c a c i a s de detección y colección

1 de carga para p a r t í c u l a s mínimamente i o n i z a n t e s .

' CLASIFICACIÓN DOE Y DESCRIPTORES: 662000/440104. Charged P a r t i c l e D e t e c t i o n . Caiorimetry. High Energy Physics. Hadrons.

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CIEMAT-712 ¡

Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas ' Instituto de Investigación Básica.- Madrid. '

"Prestaciones de una celda prototipo de un volumen de ! placas paralelas para un calorímetro rápido de hierro y ¡ gas." •

BIZZETI.A.; CIVININI,C. ; D' ALESSANDRO, R. ¡ FERRANDO, A. ; MALININ.A.; MARTÍNEZ-LASO, L. ; ' POJIDAEV.V. (1993) 20 p p . , 5 f i g s . , 7 r e f s . '

Presentamos l o s primeros t e s t s de a a p l i c a c i ó n de l a técnica de cámaras do p l a c a s para l e l a s en e l diseño de un c a l o r í m e t r o de muestreo de h i e r r o / g a s , muy rápido y r e s i s t e n t e a" la r a d i a c i ó n , que s e r í a adecuado para su u t i l i z a c i ó n en l a s regiones muy hacia a d e l a n t e de l o s d e t e c t o r e s LHC y basado en e l uso de p l a c a s de h i e r r o de gran e s p e s o r . !

Hemos c o n s t r u i d o una celda p r o t o t i p o c o n s i s t e n t e en t r e s p l a c a s p a r a l e l a s de h i e r r o (17 mm de e s p e s o r ) . Presentamos lo;; r e s u l t a d o s sobre e f i c a c i a s de detección y colección de carga para p a r t í c u l a s mlnimaraent.fi i o n i z a n t e s .

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CLASIFICACIÓN DOE Y DESCRIPTORES: 662000/140104. Charged P a r t i c l e Detection. Caiorimetry. , High Energy Physics. Hadrons. | :

CIEMAT-712 ¡

Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas ' Instituto de Investigación Básica.- Madrid. '

"Prestaciones de una celda prototipo de un volumen de ¡ placas paralelas para un calorímetro rápido de hierro y '

! g a s . " i

i BIZZETI,A.¡ CIVININI,C.; D1ALESSANDRO,R.; FERRANDO,A.; MALXNIN,A.; MARTÍNEZ-LASO,L.; '

1 POJIDA£V,V. U993) 20 p p . , 5 f i q s . , 7 r e f s . ' 1 Presentamos l o s primeros t e s t s de l a a p l i c a c i ó n de l a t é c n i c a de cámaras de p l a c a s para 1 l e l a s en e l diseño de un c a l o r í m e t r o de muestreo de h i e r r o / g a s , muy rápido y r e s i s t e n t e a~ i l a r a d i a c i ó n , que s e r l a adecuado para su u t i l i z a c i ó n en l a s regiones muy h a c i a a d e l a n t e 1 de l o s d e t e c t o r e s LHC y basado en e l uso de p l a c a s de h i e r r o de gran e s p e s o r .

1 Hemos c o n s t r u i d o una celda p r o t o t i p o c o n s i s t e n t e en t r e s p l a c a s p a r a l e l a s de h i e r r o 1 (17 mra de e s p e s o r ) . Presentamos l o s r e s u l t a d o s sobre e f i c a c i a s de detección y colección I de carga para p a r t í c u l a s mínimamente i o n i z a n t e s .

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