Liquid Argon Detector Developments at Ciemat. Participation of Ciemat at the ArDM experiment in Canfranc. Luciano Romero Manuel Daniel María de Prado

Index 1.Motivations. 2.Liquid argon detector development at Ciemat. a.Basic Infrastructure. b.Detector accesories. c.Drift Chamber. 3.Participation in ArDM experiment. 4.Tasks and Objectives of this project. 5.Schedule chart. 6.Project budget.

1. Motivations During 20 years the Ciemat built wire drift chambers for the big experiments at Cern (L3, CMS) When CMS was finished, a new detector development program was launched at Ciemat using liquid argon technology. Liquid argon drift detectors are the natural refinement of gaseous wire chambers. This research program was supported both by the Ciemat directorate and the high energy physics group (CICYT FPA ). The Ciemat directorate is interested in the research of detector technologies with possible medical aplications. Liquid argon detectors may be used as a PET detector.

1. Motivations At the same time, we get involved in the ArDM experiment for dark matter detection in the Canfranc laboratory. This application for financing has two aims: 1- Complete the development of the CIEMAT liquid argon detector. 2- Fulfill our commitment with the ArDM experiment.

2. Detector development at Ciemat a)We wanted to install at CIEMAT a basic infrastucture with a high vacuum system, cryogenic facilities and gas system that allows us to develop liquid argon detectors. This infrastructure is an asset for the future because may be useful to test and develop future detectors. b)Development of ancillary instrumentation for liquid argon detectors. Level sensor. Oxygen contamination sensor OXISORB purifier. Electronic purifier.. c)Development of a dual drift chamber. Mechanical design and construction of the chamber Development of the read out electronic. Test of the chamber with cosmic muons. d)Measurement and PET reconstruction of a pointlike positron source.

2a. Basic infrastructure. 450 liters liquid nitrogen dewar. 2 cryostats of 70 liters, high vacuum grade, for liquid argon. Turbomolecular pump for high vacuum.

2a. Basic infrastructure. Liquid nitrogen distribution system. Cryogenic filling electronic control. Crane. Gas distribution system. Alarm system for personal security. Sensor of atmospheric oxigen concentration. Ambient air renovation pump. Autonomous breathing masks.

2b Detector ancillary systems Level Sensor –Capacitive transducer. –Read out electronic Cleaning system. –In order to clean the liquid argon of electronegative elements, like oxigen, a chemical absorber is used (OXISORB). –To be included in the gas system. In parallel, an innovative electronic cleaning system, developed by us, will be tested.

2b Detector ancillary systems Oxygen contamination sensor. –Is a small drift chamber. –Photoelectrons are produced in its cathode by a pulsed xenon flash lamp. –The difference between the signals of the electrons departing the cathode and the electrons arriving to the anode is a measurement of the oxigen contamination.

Two cells of 100x100x180mm each. Each cell is made of. –Signal cables. –Layer of 32 sensor wires. –Layer of 32 induction wires. –GEM. –Extraction of electrons from LAr. –Drift electrodes. –High voltage divider. –Transparent cathode. –Photomultiplier for the trigger. With a thin layer of TPB (wavelength shifter) Total number of channels: 128 A hole between both cells allows to introduce samples. 2 c Drift Chamber

2 c Read out Electronics. The electronics use commercial signal preamplifiers and shapers (CR-110 and CR-200 from CREMAT). A printed circuit board with 16 channels has been designed. ADCs and TDCs for data adquisition are commercial boards from CAEN. The firm CAEN is developing, for ArDM, a new data taking system optimized for liquid argon detectors. We are interested in adquiring a 128 channels unit. Out preamp Out amp Out shaper CAL in Signal CAL is 8mV in 1pF (8fC)

3. Participation in ArDM experiment (Canfranc) Because of the small size of our group, our involvement in ArDM is limited. Our contribution to the construction effort is the design and construction of mechanical parts. These tasks are easied by the excellent mechanical workshop of CIEMAT. The 30 drift electrodes of the ArDM detector have already been produced.

3. ArDM detector and drift electrodes. (CERN)

3. Neutron shielding for ArDM. We have the commintment with ArDM for the design and construction of the neutron shielding. We have designed a cylindrical container, 3m diameter and 3m heigth, to be filled with polyethylene pellets. The total volume of the container is 16,5 m 3. The total amount of polyethylene is 10 tons.

3. Neutron shielding container

3. Top view of the neutron shielding container.

4. Tasks and Objectives of this project. This project is continuation of previous efforts to build a liquid argon detector. The duration of the project is two years. With respect to the 128 channels CIEMAT detector, the first objective of the project is to put it in working condition. The milestone of this objective is the PET reconstruction of a pointlike positron source located in the central hole. This objective is to be achieved in the first year of the project. In the second year of the project, we want to improve the spatial resolution of this detector by a factor 4, from 2.5 mm to 0.6 mm.

4. Tasks and Objectives of this project. On the matter of our participation in the ArDM detector, our objective in the first year of the project is to fulfill our commitment of building the detector neutron shield. During the second year of the project, we want to participate in the detector data acquisition. Another aim of this project is the writing of a doctoral thesis by one of us. (M. de Prado).

5. Schedule Chart

6. Project budget An amount of 10.9 K€ is requested for small instrumentation of the CIEMAT detector. –HV power supply. –ADC –Capacimeter. –High vacuum hardware. This amount is to be spent in the first year of the project.

6. Project budget We request 15k€ to install the personal safety system and 3 k€ for the gas system. This amount is to be spent in the first year of the project. In the second year we request 30k€ to buy a CAEN data acquisition system

6. Project budget For our participation in the ArDM experiment we request 30k€ for the 10 tons of polyethylene pellets and 3k€ for the shield container.

6. Project budget Finally, we request money to travel. 4800€ during the first year 6800€ in the second year, including long term travels to Canfranc.

6. Project budget The total amount we request is € € during the first year 39760€ in the second year.