LNGS Wiki Pages - gssi-cryogroup:gagg-nd

01_07_2024

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

* Regarding the LiI detector * the DAQ sometimes crashed; try to debug by using the low-level software of the CAEN module this week * till now, the detector has collected more than two weeks of background data * start new measurements with calibration sources (after fixing the DAQ, take data with the Am-Be source)

02_09_2024

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

* Regarding the LeBr3 detector * alpha saturation at 1.5 kV because the digitizer dynamic range is above the limit * HV scanning: the energy resolution is not affected too much; at around 2 kV, the PMT saturates * Next step: fine-tuning the PSD parameters

08_10_2024

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

* Regarding the GAGG detector * Gio gave the talk about the gagg detector and got good response at the LRT conference * fixed the Octopus bugs and added new features for the PSD, details see * ideas about determining the half-life of the 152Gd alpha decay (Q = 2204 keV)

9be_gamma_n_8be_reaction

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

9Be(γ, n)8Be Photonuclear reaction: * overcome the binding energy of nucleus * threshold at E=1.665 MeV for 9Be 1) Setup and source Setup for the γ-n reaction, and the viewpoint from x-y and x-z Point source: γ-rays at 2614 keV for

15_01_2025

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

* (γ,n) reaction * compare neutron flux with different gamma sources (Th or U? for U, 2.4 MeV is close to the resonance energy) * increase the neutron flux by increasing source activity or Be target thickness * measurements with varying thicknesses of the PE moderator for MC validations

15_07_2024

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

* Regarding the LiI detector * the DAQ is fixed by switching the USB cable to another port * the detector will collect more than two weeks of background data * an amplifier that doesn't modify the pulse shape is used to reduce random noise events

18_12_2024

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

* Regarding the GAGG detector * writing paper, will add DC analysis, and contamination values * start the Be(γ, n) reaction, hopefully this Friday * thermal neutron Am-Be data processed * LaBr3 detector * data exposure doubled, around 25 days

23_10_2024

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

* Regarding the GAGG detector * adjust the fitting of 152Gd * do a simultaneous fit to estimate the contamination values * Next step * test the time reconstruction of the DAQ using a pulse generator * understand the 7 ms coincidence:

25_09_2024

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

* Regarding the GAGG detector * preliminary calculation for the contamination levels for the decay chains, details see * discussed the structure of the talk for the LRT conference

29_07_2024

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

* Regarding the LiI detector * resampling (by a factor of 10) is fixed in the DAQ software * start new measurements with the Am-Be source with different thickness of PE shield * check the pulse shape of different particles and look at the detector's capabilities for particle identification

activity_measurement

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

2025/01/31, created 2025/02/04, updated Chain Decay Activity [mBq/kg] Reference 232Th 232Th α ? (Is Found) preliminary_activity (section 3) 224Ra → 220Rn → 216Po → 212Pb α triplet 2.499 ± 0.056 (220Rn → 216Po) 2.329 ± 0.078 (triplet)

alpha_triplet

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Search for 3 signals from the alpha decay chain: 224Ra -> 220Rn -> 216Po -> 212Pb by Silvia The energies and half-life times of the 3 alpha decays are: Q-value [keV] α Energy [keV] t1/2 224Ra 5789 5685 3.6 d 220Rn 6405

alpha_triplet_2nd_episode

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Tentative search for 3 signals of the alpha decays triplet from the 235U chain: 223Ra -> 219Rn -> 215Po -> 211Pb by Silvia (July-August 2024) The energies and half-life times of the 3 alpha decays are: Q-value [keV] α Energy [keV] t1/2 223

alpha_triplet_2nd_episode_update

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Alpha decays triplet from the 235U chain: 223Ra -> 219Rn -> 215Po -> 211Pb Final alpha energy calibration and contamination evaluation by Silvia (January 2025) Updated analysis with the new event reconstruction (v3) and the corrected event time.

alpha_triplet_labr3

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Study of the 223Ra → 219Rn → 215Po → 211Pb alpha triplet, preliminary calibration curve for alpha particles. by LorenzoA (September 2024) In this page I report the alpha analysis regarding the background run of LaBr3 from 26-08-2024. The total measurement time is 30 minutes.

alpha_triplet_update

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Alpha decay triplet from the 232Th chain: 224Ra -> 220Rn -> 216Po -> 212Pb First energy calibration and contamination evaluation by Silvia (January 2025) Updated analysis with the new event reconstruction (v3) and the corrected event time. The energies and half-life times of the 3 alpha decays are:

am-be_neutron_source

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Am-Be neutron source 1) Setups and source spectrum Setup with the standard PE moderator in light blue (X-Y) X-Z The borated PE is in yellow, and the air is in green, the crystal is magenta and sealed by the stainless steel. The same applies to the following sketches.

background_data_from_the_gagg_-_detector_response_for_alphas

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Second background run about 2.5 months data-taking Pulse shape discrimination setting the discrimination parameter to PSD = 0.024: * Below the cut value, events are categorized as alphas; * above the value, events are β/γ PSD versus integral

bkg_removal_for_neutron

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Study of the 212Bi (35.94 %)-> 208Tl -> 208Pb decay in the 3-5 MeV gamma region by LorenzoA (September 2024) The energy and the half-life times of the two decays are: Q-value [keV] α Energy [keV] t1/2 212Bi 6207 6051 (69.9 %)-6089 (27.1 %)

calibration_data_from_the_gagg_-_detector_response_for_gamma_rays

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

calibration files GAGG_SelfTrigger_HV_1.4kV_232Th_20231207_153633.root GAGG_SelfTrigger_HV_1.4kV_238U_20231207_154713.root GAGG_SelfTrigger_HV_1.4kV_241Am_20231207_155818.root Source Energy [keV] 232Th 238.632 583.191

daq_instructions

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

DAQ How to run * Connect to the DAQ computer (you must use the LNGS cable network or the LNGS VPN: ssh my_user_name@172.17.4.212 * Load the DAQ software: $ source /software/LoadGAGG-DAQ.sh * Prepare a TOML config file following the examples in the /software/config

end_of_the_7_ms_saga

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

End of the 7 ms saga? Author: Gio Date: November 5, 2024 Timestamp fix in DAQ software While doing the tests with the pulser (last week) I noticed that we could incur in some truncation issue when computing the part in second and nanosecond of the timestamp, and later on also in the calculation of the delta-t between events.

first_month

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

A first look at a month of data from the GAGG 2024/2/27, AndreaM We analyse roughly one month of data acquired with the GAGG underground, from 2024/1/15 to 2024/2/12. The dataset is 29 days long, the total number of acquired events is 38193181, which corresponds to a rate of ∼15 Hz.

gagg_wafer_measurement_campaign

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Measurement We have 14 wafers. Each wafer has a diameter of 5 cm, and a thickness of 2 mm. The measurement usually takes one or two weeks. Processed data Each data file lasts three hours. The processed background data for different types of wafers can be found under these directories, (T: standard, CF: low light yield, fast time response , HL: high light yield)

hv_scan

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Calibration files Data was taken on August 22. We used a Th232 source and for every file the measurement time is 2 minutes. The voltage was varied from 1500V to 1200V with steps of 50V. The files used for this analysis are listed below. LaBr3_H2431_1500V_UG_Th_20240822_165354.root

labr3-toy_analysis

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Study of the parameters to be used in the analysis of the 215Po decay in LaBr3 crystal and results of the analysis by Silvia (May - June 2025, update October 2025) 1) DEFINITIONS OF THE ADC INTERVALS for the study of the 215Po -> 211Pb decay According to our discussion on the data analysis for the measurement of the Po215 decay lifetime, I analyzed the

labr3

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Detector components Crystal Producer: Epic Crystals Serial number: 20230104 Dimensions: diameter 50mm, height 50mm [ LaBr3 datasheet] PMT PMT model: R375 Serial number: SB4437 Voltage divider: Hamamatsu E1435-02 Polarity: negative [ PMT generic specs] [ PMT detailed specs] Mounting

labr3_215po

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Study of the half-life of 215Po -> 211Pb by Silvia (January 2025) A few slides with preliminary results:

labr3_measurement_campaign

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Giovanni, 01.08.2024 HV scan * 900 V * LaBr3_900V_UG_Am_20240801_094057.root -> 1 min, threshold too high, visible some gamma and alpha peak? * LaBr3_900V_UG_Th_20240801_094933.root -> 1 min, 10 RMS threshold, visible several peaks. I suspect the upper region are mostly alphas (different Chi2)

lii_measurement_campaign

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

LiI measurement campaign First campaign - no amplifier Summary of the runs * From LiI_SelfTrigger_HV_750V_UG_Thermal_20240530_205303.root to LiI_SelfTrigger_HV_750V_UG_Thermal_20240627_112642.root Partly good, 30 min, DAQ crashing randomly because we used the wrong USB port on the DAQ laptop. Only files with an actual 30 min duration are usable.

preliminary_activity

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Preliminary activity measurement fot the GAGG by LorenzoA (September 2024) 0) Analysis method used for the measurement of the activity We have investigated in previous notes the alpha triplets 224Ra -> 220Rn -> 216Po -> 212Pb and 223Ra -> 219Rn

processed_data_v2

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Data processing version 2 Data location: /data/Reconstructed_GAGG_v2 Reprocessed only GAGG background data so far. New features * Data processed with a single config file for all runs, available at * Added average pulse for alpha events * Added average power spectrum for alpha events

prototype_154gd_measurement

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Dedicated measurements for 154Gd decay 1) First measurement with Pb only data taken from GAGG_1.4kV_UG_bkg_AmpX10filtered_20260312_100728.root to GAGG_1.4kV_UG_bkg_AmpX10filtered_20260316_142013.root 2) Second measurement Moved the setup to SABRE which has a better shielding (15 cm Pb + 5 cm Cu + N2 flushing), and the data are taken from

prototype_detector_characterization

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Prototype detector characterization Detector assembly Above-ground measurements First background campaign Detector moved underground in the Gator box and installed in the borated-PE shielding borrowed from the Baudis group.

prototype_gaag_detector_geometry

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

The detector components are detailed regarding the specific size and material Detector geometry from the viewpoint of X-Y Material shape size [cm] density [g/cm3] GAGG (Gd3Al2Ga2O12:Ce) cylinder Φ=5, h=5 6.63 Stainless steel (304)

pulser

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Pulser test In order to investigate the issue of the apparent 7 ms half-life from the 215Po decay, I acquired some short runs by injecting pulser-generated events directly into the digitizer. In all cases, the injected signals are square pulses with 1 us duration and negative polarity, and the acquired windows are 2us long.

pulser_testing_time_resolution_and_dead_time_of_the_digitizer

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Time resolution and dead time measurements with the pulser generator In order to quantify the instrumental uncertainty for the precise half-life measurement of the 215Po, we measure the time resolution and the dead time of the digitizer by injecting pulser-generated events directly into the digitizer. In all cases, the injected signals are bursts of two pulses in every 5 ms. To mimic the real data, the square pulses have a similar amplitude as the real events and negative polarity, and the acqu…

searching_for_the_rest_alpha_decays

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Newly processed dataset new discrimination parameter: * For selecting the 152Gd alpha decay events: nSigmaBetaGamma < -3 ; * For selecting the high energetic alpha peaks: Chi2 < 0.004 && nSigmaBetaGamma < -4.5 As an example, pile-up events are seen below:

simulation_with_the_lii_neutron_detector

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

spring2025_plan

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

1. Introduction We plan to publish a paper about the precise measurement for the half-life of the 215Po α-decay using LaBr3 scintillation detector. For this purpose, we need to analyze the systematic uncertainty in detail. This page lists the possible factors we need to consider. The systematic uncertainty will include two parts, one is from the instrument uncertainty, and the other is contributed by the analysis.

start

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

GAGG Neutron Detector Wiki Plan of the GAGG project for the next months (Andrea&Giovanni, July 2024) Plan of the LaBr3 paper for the next months (LNGS, March 2025) Detector(s) Technical specifications and drawings Pictures LaBr3 DAQ DAQ instructions Data Prototype detector characterization Prototype detector background LiI measurement campaign LaBr3 measurement campaign GAGG wafer measurement campaign Prototype 154Gd measurement Analysis software Data processing version 2 (Gio, …

study_of_alpha_spectrum

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Study of the alpha spectrum and alpha decays. Preliminary energy calibration. Silvia & Andrea, 11-7-2024 Analysis of background runs from 16-1-2024 to 3-4-2024 Total measurement time 77.5 days Total events 106028688 (15.8346 Hz) Total gamma events 95831351 (14.3117 Hz)

study_short_windows

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Search for 212Bi-212Po decay in the short time windows data 2025/01/28 AndreaM We acquired 27 days of data from the GAGG with a special acquisition time window. This time window is 400 ns long, much shorter than the usual one. This feature opens up the possibility to detect the decays with very short half-life, in particular the

summer2024_plan

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Plan of the GAGG project for the next months 2024/7/18 Andrea & Giovanni 0. Introduction This page is meant to summarise the general plan, goals and list of steps for the GAGG project roughly to the end of this year. A first important deadline is the

total_alpha_decays

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Approximate evaluation of the total alpha contamination by Silvia (February 2025) Here I try to evaluate of the total alpha contamination of the crystal. Taking into account the decay chains of 232Th, 235U and 238U, I try to estimate the activity of each isotope, in order to reproduce the observed ADC spectrum.

uncertainties

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Systematic uncertainties of the 215Po half-life measurement In order to quantify the systematic uncertainty of the precise half-life measurement of 215Po, we take into account both the instrumental and analytic uncertainties, as mentioned before. We performed dedicated measurements to estimate the instrumental uncertainty.

wafer

Anonymous (anonymous@undisclosed.example.com) — 2026-06-09T10:05:34+00:00

Performance and Contamination of 14 GAGG wafers The data storage is referred to Reminder: T represents a standard wafer, which is the same type as the prototype; CF has a low light yield but fast time response; HL has a high light yield but slow time response